Saturday, December 3, 2011

BUSINESS PRACTICE ASSIGNMENT

Guarantees:Retailers and other such suppliers guarantee their goods will:

Be of acceptable quality 
Be fit for a particular purpose that you asked about.
Match the description given in advertisements or sales brochures, or by the sales assistant.
Match the sample or demonstration model.
Be owned by the consumer, once purchased.
Be a reasonable price, if no price or pricing formula has been previously agreed.
Manufacturers (this includes importers) in New Zealand guarantee that:
Spare parts and repair facilities will be available for a reasonable time.
They will honour any written warranty that comes with their products.
Goods are of acceptable quality.
Goods match their description.
Service providers guarantee their services will be:
Performed with reasonable care and skill.
Fit for the particular purpose they were supplied for.
Completed within a reasonable time.
A reasonable price, if no price or pricing formula has been previously agreed.

Acceptable quality

This means goods:
Do what they are made to do.
Are acceptable in appearance and finish.
Are free from minor defects.
Are safe and durable.
The Act's terms "reasonable" and "acceptable" are deliberately open-ended. It depends on what a reasonable consumer would think was acceptable based on the nature of the goods, the price, and any statements that have been made about the goods. A concert violin is required to meet a higher standard than a child's cheap instrument. Ultimately a tribunal referee or a judge may have to decide what is reasonable or acceptable in the circumstances.
If a defect was pointed out to you before you bought the good, then it doesn't count towards making it unacceptable.
A warranty is the manufacturer’s or trader’s guarantee that goods or services will last as long as the warranty says it will.
The terms and conditions of the warranty are decided by the manufacturer or trader and might cover more or less than the Consumer Guarantees Act offers.
The warranty doesn’t replace your rights under the Consumer Guarantees Act. And the trader can’t tell you that it does.
Always read the fine print because this will enable you yo know what the conditions are and some warranties may not appear to be as they seem.

Quotations
quoate is as follows
Name and name of customer: 
date:
Items listed(parts extras):
labour:
price of the above and below:
GST if you want to
maybe an explanation of what needs to be done to justify this quote
When one operates a business involving the offering of goods and/or services, it is common practice to give a quote before taking on a job. The best way to ensure that a quote will be legally binding is to do all of the following:
  • record the quote in writing, preferably as part of written terms of trade 
  • give the written quote to the prospective customer
  • keep a copy for yourself
  • get the customer to sign a copy of the quote (or the terms of trade if you have used them) before supplying the goods or services 
Cultural issues.
This is usually language barriers that occur with misunderstandings either as a customer or a worker. Being aware of this is important as this can lead to vague understanding of price/cost of jobs or what was asked to be done.
FAIR TRADING ACT

The Fair Trading Act 1986 protects you against being misled or treated unfairly by traders or shops. 
The Act prohibits what is called "misleading or deceptive conduct, false representations and unfair practices". It also sets out when information about certain products must be disclosed to consumers, and helps ensure products are safe.
The Act applies to everyone in trade. As well as traders and shops, the Act covers government agencies and state-owned enterprises. Most of the Act does not cover private sales.
The difference between the Fair Trading Act (FTA) and the Consumer Guarantees Act (CGA) is that, in general, the FTA covers claims about products and services prior to sale and the CGA covers the quality of those products and services after they have been bought.

HEALTH AND SAFETY IN EMPLOYMENT ACT 1992 (HSE ACT)

The object of the Health and Safety in Employment Act 1992 is to promote the prevention of harm to all people at work, and others in, or in the vicinity of, places of work.
The Act applies to all New Zealand workplaces and places duties on employers, the self-employed, employees, principals and others who are in a position to manage or control hazards.
The emphasis of the law is on the systematic management of health and safety at work. It requires employers and others to maintain safe working environments, and implement sound practice. It recognises that successful health and safety management is best achieved through good faith co-operation in the place of work and, in particular, through the input of those doing the work.
The Department of Labour administers and enforces the HSE Act in most workplaces.
The Maritime New Zealand and Civil Aviation Authority administer and enforce the Act in the maritime and aviation sectors respectively. New Zealand Police works with the Department to enforce the Act in relation to commercial vehicles.

LAND TRANSPORT REGULATIONS FOR TRAILERS

earn the basics and towing should be safe

A simple trailer is the commonest variety and has a single axle. Even a simple trailer can put a large weight on the rear of a tow vehicle and potentially interfere with steering, braking and traction by unweighting the front axle.

Size is important

Make sure the trailer coupling and the tow ball are an appropriate fit. Modern tow balls are 50mm in diameter, slightly larger than older ones (47.6mm).  All trailers require a safety chain in case the coupling device breaks. The chain must be short enough that it prevents the trailer coupling from dragging on the ground.

What the law requires

Your trailer requires a Warrant of Fitness (WoF) and registration.

If the trailer hasn't been used for a long time, check tyre pressures, tread depth, wheel bearings and whether the warrant is still current.

It must have amber or white forward-facing side lights if its width exceeds two metres and if it was registered after 1977. If it is wider than 1.5 metres it requires two tail-lights. If first registered after 1977, it must also have two stop lights. However the latter are not needed if arm signals or tow vehicle stop-lights can be seen by following drivers.

Similar rules apply for indicators. Two red reflectors are also required by law and a white light to show the trailers registration.

The trailer load

When packing the trailer, ensure the load is evenly distributed. If it is unbalanced, it may cause swaying.

Ensure your load is properly secured. No part of the load should be in contact with the ground, and nor should any part of the load extend more that 1.25m either side of the centre line of the trailer.

If the load extends, more than 1.0 metre behind the trailer, attach a white, red, orange or yellow fluorescent flag to indicate where the load ends. The load must not extend more than 4.0m behind the axle or the mid-point of the tow trailer axles

Check there is a downwards force - around 30-40kg - on the towball because any less and trailer stability may be affected. The drawbar should appear level or slightly nose down

Avoid filling your hatch or boot with gear as this will further unload the front axle.

DANGEROUS GOODS ACT
(NOTE THIS ACT DIFFERS DEPENDING ON YOUR COUNCIL)
                               LICENSING

   9. Licensing of premises for storage of dangerous goods---(1) A local
 licensing authority may, on application in such form as it may require
 and after receiving any prescribed fees, grant licences for the storage
 of dangerous goods within the district of that local licensing
 authority.

   (2) The Chief Inspector may grant licences for the storage of
 dangerous goods within any district, area, or place for which he is the
 licensing authority.

   (3) Notwithstanding subsection (1) of this section, where any premises
 to which this Act applies are situated partially within the district of
 one licensing authority and partially within the district of another
 licensing authority or other licensing authorities, the Chief Inspector
 may designate any one of those licensing authorities to be the sole
 licensing authority for those premises.

   (4) On any application for a licence under this section, the licensing
 authority may---
   (a) Grant the licence in accordance with the application; or
   (b) Grant the licence subject to such modifications of the proposals
         as it or he thinks fit, having regard to the interests of public
         safety or the safety of any person or the protection of any
         property; or
   (c) Refuse to grant the licence if it or he thinks the interests of
         public safety so require.

   (5) The licensing authority in granting, or after having granted, any
 licence under this section, may impose such further conditions as it or
 he thinks fit in the interests of public safety or the safety of any
 person or the protection of any property:

   Provided that the applicant for a licence or the holder of a licence
 may, within 14 days after the imposition of any further conditions and
 notwithstanding section 14 of this Act, object in writing to all or any
 of the further conditions to the licensing authority which imposed them,
 and that licensing authority shall refer the matter to the Chief
 Inspector who may reject, modify, or confirm the further conditions
 being the subject of the objection and the licensing authority shall
 advise the objector in writing of the Chief Inspector's decision. For
 the purposes of an appeal under section 14 of this Act the decision of
 the Chief Inspector shall be deemed to be the decision of the licensing
 authority.

   (6) Any person who commits a breach of any condition imposed by a
 licence or by a licensing authority under this section commits an
 offence against this Act.
     Cf. 1957, No. 20, s. 16

                             Regulations

   35. Regulations---The Governor-General may from time to time, by Order
 in Council, make regulations for all or any of the following purposes:
   (a) Prescribing the quantities of dangerous goods that may be stored
         or used in premises in respect of which licences are issued
         under this Act for the storage of dangerous goods, or in depots
         established or maintained by local authorities pursuant to this
         Act, or in premises which are not required to be licensed, and
         the manner in which and the conditions subject to which any such
         goods shall be so stored or used:
   (b) Prescribing the circumstances under which premises are not
         required to be licensed for the storage and use of dangerous
         goods:
   (c) Prescribing, with respect to the licensing of premises and to the
         establishing by local authorities of depots for the storage of
         dangerous goods, conditions as to the location of those premises
         and depots, and their construction, equipment, and maintenance:
   (d) Prescribing the fire-fighting equipment that must be kept in or
         provided for use in premises in respect of which licences are
         granted under this Act or in premises which are not required to
         be licensed, or in depots established by local authorities under
         this Act, and on vehicles used for the carriage of dangerous
         goods, and providing for the maintenance and periodic testing of
         that equipment:
   (e) Prescribing rules to be observed in the interests of public safety
         in any place where dangerous goods are stored, used, handled, or
         exposed, and in the carriage of dangerous goods:
   (f) Regulating the loading, unloading, and carriage of dangerous
         goods, and the routes to be taken by vehicles carrying dangerous
         goods:
   (g) Regulating the construction of, and the fittings and appliances to
         be carried on, vehicles carrying dangerous goods, and providing
         for the approval of tank vehicles for the carriage of dangerous
         goods:
   (h) Regulating the granting, transfer, amendment, and renewal of
         licences granted under this Act:
   (i) Prescribing the method of packing dangerous goods, and the marks
         to be placed on dangerous goods or the containers of dangerous
         goods and on the outer packages of those containers:
   (j) Prescribing the construction of testing apparatus, the manner of
         testing petroleum and other flammable liquids or materials, and
         the method of ascertaining the flash point of such liquids and
         materials:
   (k) Prescribing fees to accompany applications for granting and
         renewing licences, and fees for approving equipment, appliances,
         and vehicles, and fees for testing dangerous goods:
   (l) Regulating the disposal or repair of containers that have
         contained dangerous goods, and the handling and cleaning of such
         containers:
   (m) Prescribing requirements to be met in the construction,
         manufacture, installation, testing, or servicing of any
         container, pipeline, plant, pump, or other equipment used or
         intended to be used for, or in connection with, dangerous goods:
   (n) Prescribing fees payable in respect of an initial inspection by an
         Inspector of premises which are subject to the provisions of
         this Act or regulations made under it, but which are not
         required to be licensed:
   (o) Prescribing offences in respect of contravention of or
         non-compliance with any regulations made under this Act or any
         requirement or direction made or given pursuant to any such
         regulation; and prescribing penalties not exceeding [$5,000] in
         respect of any offences prescribed under this paragraph and, in
         the case of continuing offences, prescribing further penalties
         not exceeding [$1,250] for each day during which the offences
         have continued:
   (p) Providing generally for preserving the public safety or the safety
         of any person or the protection of any property from the threat
         of fire or explosion or other hazard resulting from dangerous
         goods:
   (q) Providing for such matters as are contemplated by or necessary for
         giving full effect to the provisions of this Act and for its due
         administration.
     Cf. 1957, No. 20, s. 38

       In para. (o) the expressions ``$5,000'' and ``$1,250'' were
     substituted for the expressions ``$1,000'' and ``$250'',
     respectively, by s. 2 (b) of the Dangerous Goods Amendment Act 1983.

COUNCIL BY-LAWS
If you’re going to start your own business, buy an existing business or change or expand your current business there are some things about where you want to locate and how you will operate your business that you should consider. Any environmental effects of locating and operating your business are considered under the Resource Management Act (RMA).
Your business will probably be located and operated in a community where people live, play, shop and work.  The things you do at your business premises can affect those living around you, just as their activities can affect you.  Effects could be positive, such as added vitality for your locality, or negative, such as increased noise or decreased water quality.
The Resource Management Act requires district/city and regional councils to address these types of effects in plans that help them manage the environment. These plans contain rules and standards for activities that might affect the environment. 
If your business activity doesn’t fit within the rules and standards you may need a resource consent before you can operate. Both regional councils and district and city councils have plans and rules which could affect you setting up your business.  When the council considers your application for resource consent, it follows the processes set out in the RMA.
So… early in your planning for your new business, it pays to check out what the district/city and regional plans say about what you want to do and where you want to do it.                   Ongoing responsibilities
In setting up and operating your business, you need to be aware of your ongoing responsibilities.
If your business was established by meeting the plan rules and standards (permitted activity) you will need to continue to comply with these provisions.  If your business grows to a point that you no longer meet the plan provisions, you may need a resource consent.
If you got a resource consent to start your business you will need to comply with your consent.  This is what you said you would do in your application (how you described your business) and any conditions the council imposed on your resource consent.  This may include things like how you operate (eg, hours of operation, numbers of staff) and physical works (forming carparks, planting and maintaining landscaping, treatment of a discharge).
Unless your resource consent says otherwise you are expected to fully comply with your consent on the day you start operating.  Compliance will not wait until your cash flow is established and your business is financially stable.
There are consequences if you don’t comply.  You could face enforcement action and be prosecuted.  This can affect your ability to operate your business.

Business and environment-friendly tax changes

Businesses can claim tax deductions for environmental expenditure.  The types of deduction available are for:
  • cleaning up contaminated land
  • establishing a voluntary site restoration fund
  • costs incurred in investigating and testing options to avoid, remedy or mitigate the discharge of contaminants, and for environmental monitoring
  • improvements that prevent or mitigate the discharge of contaminants.
 HEALTH AND SAFETY IN EMPLOYMENT

2.3 Hazard management responsibilities (sections 7-10)

Sections 7- 10 of the Act set out in more detail the steps an employer must take to manage significant hazards in the place of work.
These duties complement and describe a process for meeting the employers' general duties set out in section 6 of the Act.
The process for managing significant hazards is based on the ergonomic principle that the workplace should be modified to suit people, not vice-versa. The steps are:
Identifying hazards - involves recognising things which may cause injury or harm to the health of a person, for instance flammable materials, ignition sources, or unguarded machinery (section 7);
Assessing the hazard - involves evaluating whether the hazard is significant (section 7(1)(c)) and the likelihood and degree of injury or harm occurring to a person if they are exposed to a hazard; and
Controlling the hazard - by taking all practicable steps to eliminate, isolate, or minimise significant hazards (sections 8,9,10).
Monitoring any exposure - to a hazard that has been minimised (section 10).
The control of occupational injury and disease hazards should preferably be dealt with by design or redesign, substitution, separation or administration. These controls generally eliminate, isolate, or minimise hazards in a more reliable manner than personal protective equipment.
Controls may reduce the significance of a hazard or the likelihood of it causing harm to employees or others.
Where regulations require specific methods to control the hazard, these must be complied with (see 1.6, How the Act sets more detailed standards).
It is important to regularly review the steps of hazard management, especially if there are changes in the work environment, new technology is introduced, or standards are changed.

Involving employees in hazard management

Employers have a duty to provide reasonable opportunities to employees to participate effectively in ongoing processes for improvement of health and safety in their place of work (section 19B).
This applies in particular to the processes set out in sections 6-13 of the Act.
The Act specifies circumstances where a system is required to be in place to properly canvas the views of employees. Safety and health committees and representatives provide a means for such consultation and co-operation, and their establishment is encouraged.
[Refer to the fact sheet, Employee participation]
The legal responsibility for safety and health decisions at a workplace rests with the employer, but the consultation process should help employers to reach decisions which take into account information and recommendations provided by employees or a workplace health and safety committee or representatives.

Identifying hazards

Section 7 requires employers to have in place effective methods to systematically identify hazards to employees at work. Hazards may be:
  • Previously existing;
  • New; or
  • Potential.
Having identified the hazards, employers must determine which are significant and require further action.
When an accident or serious harm occurs, an employer (and a self-employed person or principal) must notify the Occupational Safety and Health Service in the prescribed form (see 5.1, Recording and acting on accidents and serious harm). The employer must also take all practicable steps to investigate whether it was caused by a significant hazard.

What is a "hazard"?

The concept of a hazard is pivotal to the working of the Act.
A hazard is any actual or potential cause of harm.
It may occur inside or outside of a place of work.
It may be:
  • An activity;
  • An occurrence;
  • An arrangement;
  • A phenomenon;
  • A circumstance;
  • A process;
  • An event; or
  • A situation.
It includes a situation where a person's behaviour may be an actual or potential cause or source of harm to the person or another.

What is a "significant hazard"?

A significant hazard is one which may cause:
  • Serious harm (an important concept, defined in schedule 1 of the Act, which is reproduced in the Definitions section at the back of this guide). This includes death and many occupational illnesses and injuries that may be sustained in a place of work; or
  • Harm - the severity of which may depend on how often or how long a person is exposed to the hazard - such as occupational overuse syndrome; or
  • Harm that cannot be detected until a significant time after exposure. This includes long-latency diseases caused by exposure to hazardous substances - such as asbestosis, neurotoxicity, emphysema, and other diseases of occupation.

Methods of hazard identification

The Act does not specify a particular method of hazard identification, only that the chosen method is effective. It does, however, require the consideration of all accidents or near-miss incidents which lead to, or could have lead to harm - to determine if they were caused by a significant hazard. (If the hazard is significant, all practicable steps must be taken to control it.)
There is a range of hazard identification methods in common use in industry. Frequently it is appropriate to use a combination of approaches.
In all but the smallest of workplaces, it is likely that to be effective the hazard identification process will need to be recorded.
Remember again the section 19B duty for employers to give employees reasonable opportunities to be involved in hazard management processes.
Four commonly used methods of hazard identification are:
Physical inspections
This is the traditional method of identifying hazards by walking around the place of work with the aid of a checklist.
Task analysis
It may be useful to look at the tasks in each job and observe the actions of employees, while identifying the hazards involved.
Process analysis
This involves following the production or service delivery process from start to finish, and identifying the hazards involved at each stage.
Analysis of accident investigation details
This is mandatory under section 7(2) of the Act. Whenever there is an accident, "near miss", or the incidence of harm, the employer must take all practicable steps to determine the cause and whether it was a significant hazard. This corresponds with the requirement for employers to keep a register of every accident or incident.
Depending on the approach used and other factors, such as the type and size of the workplace, procedures may range from a simple checklist for a specific piece of equipment or substance, to a more open-ended appraisal of a group of related work processes.
Whichever method(s) is used, it may be useful to develop a hazard checklist for the particular place of work or process.
Information from designers or manufacturers, material safety data sheets, product labelling, or other sources of information should all be systematically reviewed as part of the hazard identification process.
Where appropriate, advice should be sought from specialist practitioners or representatives.
In summary, to meet the requirements of section 7 an employer should expect to produce a list of hazards present in each place of work - with significant hazards clearly identified.





          starting & charging systems.
Inertia type: 
Inertia starters incorporate low weight in proportion to the torque capacity of the starter. a perk of using inertia starter is their low current drag on the electrical system. the pinion gear is forced forward to mesh with the flywheel from the spinning of the armature. torque overload consists of a disk clutch under adjustable spring pressure.
 

Pre engage:
Pre engaged starters prevent an awful lot of wear on the ring gear and Bendix gear. They were a big jump forwards in reliability. Non preengaged starters work by throwing a spinning cog at the ring gear on the flywheel to turn the engine. It will only disengage when the engine reaches sufficient speed to throw the cog out again, or the igntion key is turned back from 'start'.  A lot of wear as you can imagine.  Pre engaged have the cog already in place on the ring gear before the starter motor turns.  Once the ignition key is turned back to 'Ign' it disengages and waits until the ignition is turned off before re engaging with the ring gear.


Reduction gear
The operator closed the key-operated starting switch.A small electric current flowed through the starter relay coil, closing the contacts and sending a large current to the starter motor assembly.One of the pole shoes, hinged at the front, linked to the starter drive, and spring-loaded away from its normal operating position, swung into position. This moved a pinion gear to engage the flywheel ring gear, and simultaneously closed a pair of heavy-duty contacts supplying current to the starter motor winding.The starter motor cranked the engine until it started. An overrunning clutch in the pinion gear uncoupled the gear from the ring gear.The operator released the key-operated starting switch, cutting power to the starter motor assembly.A spring retracted the pole shoe, and with it, the pinion gear.


Alternator:
This is found usually at the front of the engine This works with the battery and the engine.
The alternator chargres the battery and the engine drives the alternator. This is what provides power for all the electricals while your car is running. It is driven by a crank shaft and belt.
your car would not run with out one of these as the battery can not power the car and would simply go dead if the alternator died. The name alternator come for alternating current( AC ).


Generator:
a generator is basicaly the same.
Alternators generate electricity by the same principle as DC generators, namely, when the magnetic field around a conductor changes, a current is induced in the conductor. Typically, a rotating magnet called the rotor turns within a stationary set of conductors wound in coils on an iron core, called the stator. The field cuts across the conductors, generating an electrical current, as the mechanical input causes the rotor to turn.
What two substances are mixed together to form an electrolyte in a battery?
In a car battery, diluted sulfuric acid and a water solution (electrolyte), are used together with lead plates to create a chemical reaction that produces voltage.

What three elements are required to make a petrol engine run effectively?
In a fourstroke petrol engine, the three main elements required for effective running are Air, Fuel and Spark. 


Give an explanation of ''Dwell Angle'' in a distributor.
The dwell angle is the number of degrees of rotation of the cam/distributor during which the points are closed. During each rotation of the cam/distributor, the points must open and close once for each cylinder. The points must stay closed long enough to allow the coil primary current to reach an acceptable value, and open long enough to discharge and produce a spark. As the crankshaft rotates and pistons go through their cycles, the distributor's function is to precisely control the timing of the spark. Each cylinder's spark must occur at a precise time during the rotation of the engine. The distributor is driven off a gear on a camshaft or an idler pulley in the timing chain, such that it rotates at half the speed of the crankshaft. The drive method is dependant on engine manufacturers. The engine makes two complete revolutions in the same time that the distributor makes one 360 degree revolution. 


Explain the operation of a ''Kettering Ignition System'', including all components from the battery to the spark plug.
The distributor contains a rotating cam driven by the engine's drive, a set of breaker points, a condenser, a rotor and a distributor cap. External to the distributor is the ignition coil, the spark plugs and wires linking the distributor to the spark plugs and ignition coil.
The system is powered by a lead-acid battery, which is charged by the car's electrical system using a dynamo or alternator. The engine operates contact breaker points, which interrupt the current to an  ignition coil.

The ignition coil consists of two transformer windings sharing a common magnetic core—the primary and secondary windings. An alternating current in the primary induces alternating magnetic field in the coil's core. Because the ignition coil's secondary has far more windings than the primary, the coil is a step-up transformer which induces a much higher voltage across the secondary windings.

For an ignition coil, one end of windings of both the primary and secondary are connected together. This common point is connected to the battery (usually through a current-limiting ballast resistor). The other end of the primary is connected to the points within the distributor. The other end of the secondary is connected, via the distributor cap and rotor, to the spark plugs.

The ignition firing sequence begins with the points (or contact breaker) closed. A steady charge flows from the battery, through the current-limiting resistor, through the coil primary, across the closed breaker points and finally back to the battery. This steady current produces a magnetic field within the coil's core. This magnetic field forms the energy reservoir that will be used to drive the ignition spark.As the engine turns, so does the cam inside the distributor. The points ride on the cam so that as the engine turns and reaches the top of the engine's compression cycle, a high point in the cam causes the breaker points to open. This breaks the primary winding's circuit and abruptly stops the current through the breaker points. Without the steady current through the points, the magnetic field generated in the coil immediately and rapidly collapses. This change in the magnetic field induces a high voltage in the coil's 
secondary windings.


At the same time, current exits the coil's primary winding and begins to charge up the capacitor ("condenser") that lies across the now-open breaker points. This capacitor and the coil’s primary windings form an oscillating LC circuit. This LC circuit produces a damped, oscillating current which bounces energy between the capacitor’s electric field and the ignition coil’s magnetic field. The oscillating current in the coil’s primary, which produces an oscillating magnetic field in the coil, extends the high voltage pulse at the output of the secondary windings. This high voltage thus continues beyond the time of the initial field collapse pulse. The oscillation continues until the circuit’s energy is consumed.
The ignition coil's secondary windings are connected to the distributor cap. A turning rotor, located on top of the breaker cam within the distributor cap, sequentially connects the coil's secondary windings to one of the several wires leading to each cylinder's spark plug. The extremely high voltage from the coil's secondary -– often higher than 1000 volts—causes a spark to form across the gap of the spark plug. This, in turn, ignites the compressed air-fuel mixture within the engine. It is the creation of this spark which consumes the energy that was stored in the ignition coil’s magnetic field.

Explain why the ''Heat Range'' of a spark plug is so important.
The operating temperature of a spark plug is the actual physical temperature at the tip of the spark plug within the running engine. This is important because it determines the efficiency of plug self-cleaning and is determined by a number of factors, but primarily the actual temperature within the combustion chamber. There is no direct relationship between the actual operating temperature of the spark plug and spark voltage. However, the level of torque currently being produced by the engine will strongly influence spark plug operating temperature because the maximum temperature and pressure occurs when the engine is operating near peak torque output (torque and RPM directly determine the power output). The temperature of the insulator responds to the thermal conditions it is exposed to in the combustion chamber but not vice versa. If the tip of the spark plug is too hot it can cause pre-ignition or sometimes detonation/knocking and damage may occur. If it is too cold, electrically conductive deposits may form on the insulator causing a loss of spark
energy or the actual shorting-out of the spark current.

4K gearbox

What type of gears are used for forward and reverse in a manual gearbox? Give an explanantion for your choice.
In a manual gearbox, there are two main types of gears used to transmit power, from the input shaft from the engine to the output shaft to the diff or axle. Forward gears e.g 1st, 2nd, 3rd, 4th, 5th; use helical or constant mesh gears as there is more contact surface available and they are alot quieter than straight cut gears. Reverse gear, however uses spur or straight cut gears as the gears can slot easier into place, but, are not as strong as helical cut gears. The reverse driver, driven and the reverse idler are all straight cut gear.

What is the purpose of a bualk (synchro) ring.
A baulk ring is a gold coloured, dog toothed ring that is pushed against a free spinning gear to speed up or slow down the corresponding gear before it is engaged. For example, when driving in 3rd gear, and want to change to 4th, the baulk ring will engage and speed up the 4th gear, so when the change is made, it is done smoothly as opposed to being forced into gear, which can cause real damage.

What is the purpose of a synchromesh unit? Explain the operation of a synchromesh unit.
A synchromesh unit includes the hub, slider, bearings and baulk ring. When changing gears, this unit slides either left or right depending on the gear needed. The selector fork pushes or pulls the slider, to allow the baulk ring to match the speed of the gears. When the gears are moving at the same speed, the slider will engage the corresponding gear while being limited by the synchro hub and detent system.


What type of bearings do we find in gearboxes?
Different gearboxes use different bearings, but the most common types found in a car gearbox include roller needle, caged roller and main shaft bearings. The reason gearboxes have different types of bearings is because of the amount of load each component goes through when in use. 

Give an explanation of a gear ratio.
In a gearbox, each gear has a corresponding gear of a different size. When a gear is selected e.g 4th, the ratio would be 1:1 as the gears are the same size and turning the same speed. Where as with other gears, one gear will be smaller and turn alot faster than the bigger corresponding gear.  The different gear ratio's allow different speeds to be achieved as you change through the gears.



MARINE TRANSMISSIONS

Explain the different types of gear selection systems found in an:
Outboard gearcase:
An outboard gearcase uses a dog clutch system, that works by sliding the dog clutch to engage either forward or reverse gear. When the required gear is selected, the dog clutch locks that gear onto the output or propeller shaft. This type of engagement is very rough and is noisy.

Sterndrives:
A sterndrive works by having it's gear selector located vertically in the top housing of the ''leg''.  When forward or reverse is needed, a tapered brass cone moves up or down to lock the required gear onto the shaft. The cone type engagement works alot like a baulk ring in a manual car gearbox. Normally used in boats with smaller inboard  engines, that require smooth gear engagement.



What type of gears are used in outboards and stern legs?
Give an explanation of why manufacturers choose this type of gear.
Outboard and stern leg gear cases normally constant mesh, which mean all gears are moving even when not engaged. Constant mesh gears normally use helical cut gears, as they provide more contact between the driving teeth.

Explain what a duo propeller system is and how it works?
The duo prop system was invented by Volvo Penta and works by having two counter rotating propellers. One prop is mounted on the mainshaft, while the other is mounted on the counter rotating shaft that runs through the main prop shaft. This is used for increased acceleration, straight tracking, faster planning, better handling, lower
 vibrations and noise reduction.

Why would a ''V'' drive be used instead of a standard shaft drive system?
A ''V'' drive system is used to change the direction that the  engine is mounted, and to move the bulk of the engine back towards the stern of the boat, which also creates more space . This provides easy access to the main components driveline components.


Compare a jet unit with a surface drive unit and give reasons why you would choose one system over the other.

A jet unit works by sucking up water and forcing it out at high pressure through a directional nozzle. Jet units are common in shallow waters as they are mounted level with the bottom of the hull. Jet units have some drawbacks, which are that they have no control at low speed and if debris is sucked up, the impeller can get damaged.
Surface drives are normally found on high powered inboard boats (racing), and only have 2 to 3 propeller blades in the water at any one time. Surface drives provide excellent acceleration and quick planing but, expensive to buy.
I would personally choose the jet unit over the surface drive as it is a better all round
 propulsion system.

FOUR STROKE





INTAKE stroke: on the
 intake or induction stroke of the piston, the piston descends from the top of the cylinder to the bottom of the cylinder, reducing the pressure inside the cylinder. A mixture of fuel and air, or just air in a diesel engine, is forced by atmospheric (or greater) pressure into the cylinder through the intake port. The intake valves then close. The volume of air/fuel mixture that is drawn into the cylinder, relative to the volume of the cylinder is called, the volumetric efficiency of the engine.

COMPRESSION stroke: with both intake and exhaust valves closed, the piston returns to the top of the cylinder compressing the air, or fuel-air mixture into the combustion chamber of the cylinder head.POWER stroke: this is the start of the second revolution of the engine. While the piston is close to Top Dead Center, the compressed air–fuel mixture in a gasoline engine is ignited, usually by a spark plug, or fuel is injected into the diesel engine, which ignites due to the heat generated in the air during the compression stroke. The resulting massive pressure from the combustion of the compressed fuel-air mixture forces the piston back down toward bottom dead centre.

EXHAUST stroke: during the exhaust stroke, the piston once again returns to top dead center while the exhaust valve is open. This action evacuates the burnt products of combustion from the cylinder by expelling the spent fuel-air mixture out through the exhaust valve(s).

Wednesday, October 5, 2011

TWO STROKE ENGINES

Explain how a two stroke engine works?
A two stroke works in the sense that it is a two stroke cycle.
The piston is an intake valve exhaust valve and a compressor it performs much duty's on it's own making it is lighter than 4stroke engines therefore making it more ideal for outboards, chainsaws, Radio control hobby's.

 Air, fuel and oil enters the crankshaft housing through a reed valve for every rotation of the crankshaft, this allows for fuel to go on the other side of the piston for lubrication as oil is mixed with fuel. lets start with the piston down the reed valve is down with only a bit of fuel around the crank shaft allowing fuel to travel up to the combustion chamber as the piston travels up closing the fuel flow while this happens the reed valve opens. it pushes up and compresses the fuel and air to be ignited at the top. while this is happening the reed valve has allowed more fuel in filling up the area around the crank shaft, then the piston moves down opening the exhaust outlet. just below there the piston will allow that last cycle of fuel from the crank area to come up through the fuel intake in the boar.



What is happening below and above the piston?
 Above: upwards pressure oil fuel/air intake, ignition, exhaust out. Below: air/fuel and cycled around through reed valve, lubrication, downwards pressure.



Explain what is meant, by scavenging when applied to 2 stroke SI engines?
The process of removing exhaust also it tries to bring some back in to burn wasted fuel.



Why must roller and ball race bearings be used on 2 stroke SI engine crankshafts?
These bearings roll over each other and are used in two strokes because only takes on minimum lubrication so the bearings are more effective.



Why are rollers caged in crankshaft bearings?
To help the the conrods move freely around the crankshaft and because four strokes use oil the case inside the conrod is fixed needing oil. So in a two stroke they use rollers to move around the crank shaft because oil doesn't get in there, but these rollers have grease which has a longer life.



Why must ‘split’ type bearings be used on one piece crankshafts?
because the crank shaft is made as one piece the bearings need to go inside the conrod so you can put the conrod back back on the crank shaft also they need to be taken out to be check for wear.



Why do we have pins between the piston ring gaps on a 2 stroke?
To stop the rings from spinning around



How does a reed valve work on a two stroke?
The pressure from the up force when the scavenging process happens opens the reed valves allowing fuel to enter then the piston forces the the reed shut on the way down due to pressure. The reed valve can have two metal thin plates or a circular disk shape with petal like plates going around it, 



How do you check a reed valve? 
Always check these. Look that it clicks open and closes properly then hold it up to the light to make sure you can not see any light coming through when it is closed. Make sure there is no wear or pitting.



Explain the term ovality and taper and how are they formed?
Ovality is when the shaft warps into uneven widths so when you measure with a gauge you spin the shaft on a v stands and look at the gauge for fluctuations if one side is okay the you turn it then it is 2mm out that could well be ovality. Taper is when the haft becomes worn down on one end and starts to slant downwards or the end is already tapered and needs to be checked that the angle still remains the same.



How does the piston rings seal in the bore?
The piston rings have a are wider that the piston and the rings also have a bit of springs so when the piston is set in the boar the rings natrualy want to push out this forms the seal.



What is meant by the terms groove depth, side clearance and end gap on the pistons rings?
The piston ring sits in a groove around the piston this can change when carbon builds up behind the ring.
side clearance is the distance on either side of the rings sitting in the piston. The end gap is when the ring is in the boar making sure the gap at either end is correct using a feeler gague.



Explain the difference between a 2 stroke and a 4 stroke engine?(2 stroke dry sump ,port, piston ring, cycle ,fuel, bearings)
The stroke cycles are different. for a two stroke one cycle in each direction, it has a compression stroke followed by explosion of compressed fuel on return stroke fuel air oil is taken back in. It has a dry sump meaning the oil is mixed with the fuel and the cycle lubricates and cools with oil so there is no direct oil being put through the crank shaft. The port is dictated by the piston pressure. A two stroke only has two rings.
Two strokes need bearings in the conrod and on the crank shaft because they do not cycle oil on it's own these bearings male up for less lubrication also inside the conrod they are cased so you can open them and check for wear.



4 stroke wet sump, valves, piston, cycle, fuel, bearing, camshaft.
four stoke cycle works intake, compression, combustion and exhaust. Fuel/air enters on intake on the down stroke. Up stroke the intake valve has closes and fuel/air undergoes compression. Ignition occurs called a power stroke, the exhaust valve is opened the piston moves up for the second time expelling exhaust.
four strokes have an oil gallery and require oil to be circulated through the engine to lubricate.



What is meant by each of the following terms:

(a) Mechanical Efficiency: Actual work out put of engine to ideal work out put.
(b) Thermal Efficiency: The measurement of efficiency and completeness of the combustion of fuel, if all the potential heat in fuel could be transferred as work the thermal efficiency would be 100%
(c) Volumetric Efficiency: The efficiency which the engine can move the charge in and out of pistons/cylinders, the ratio of fuel/air that actually enters during induction to the actual capacity of cylinders under static conditions. Greater induction manifold pressure means above ambient will have efficiencies above 100%