Trailers

Trailer types

There are many differant types of trailers for all differant sizes of boats from small tinnys to some as large as 30+ feet. The main ones used for baots are:

Single axle - These are genrally used for light boats and if the trailer and boat have a combined weight less than 2000kg you will not need to have brakes on this trailer.


Tandem axle - Used for heavier boats as it has 2 axles and 4 wheels which preads the load over twice as muchs which will put less strain on the axles and wheels and be easier to control.


Triple axle - These are for very large boats which are very heavy.

Trailer designs

There are 2 common designs for trailer chasis which both work really well. The two types are:

A Frame - This design has two front chasis rails that form a triangle or 'A' shape which has the coupling attached at thier apex like the one below.



Draw Bar - This design has 2 front rails meeting earlier and then a draw bar which extends from thier meeting point and then the coupling is attached to the end of the draw bar. Some of these trailers have a removeable pin and a hinge at its inner most point which allows the trailers to tilt on the draw bar which can make launching or retreving your boat alot easier. 

Trailer materials

Boat trailers are generally made from galvenized steel or aluminium with differant shapes and sizes of steel or aluminium used.

Galvanized steel - This is just mild steel but it will have been galvanized and all that means it has been dipped into a bath of Zinc. This is done as Zinc is a great coating to prevent the steel from corrosion. Above is a photo of the baths of zinc at a galvanizing plant.

Aluminium - This is a lightwieght durable and ductile metal which can have appreances ranging from silvery to dull grey. Aluminium is up to 3 times as light as steel and has a better strength than steel also but this is why it can be very expensive.

These metals come in all sorts of shapes and below are the used shapes for the trailer construction:

The most commonly used ones would be the round tube, rectangular tube, C channel and I beams. These are all used as the are the strongest. The ones used in New Zealand Are I beams but I believe the best type to use would be the rectangular as it will be strong also all the wires can be inside the steel which helps protect them from the weather and any damage.



Trailer designs for differant boat hulls

The most common forms of trailers tends to be the bunk type or the roller type. The bunk type consists of of 2 boards or rails that are covered with carpet where the hull will sit on. The roller type is a more modern where several sets of rollers support the hull and allow for easier movement of the boat when launching and retrieving your boat. There are also a few types of rollers. Keel rollers are the opnes down the centre of the trailer where the keel sits on. some off these rollers are self centreing for easier retrieving. Side rollers are the rollers that are on a steel bracket that pivots from the chasis so the boats weight can be distributed evenly on all the rollers. These rollers come in all shapes sizes and differant materials. They will range from collered plastic to rubber. This picture below shows you all the differants types. The last is a snubbing block which is in the centre of the trailer generally on the upright post where the winch is for the front of the boat to sit safetly and centre.

WOF regulations

Weight and dimensions - You can tow a trailer that's up to 2.5m wide, 4.25m high when loaded, and 11.5m long, as long as the combined car and trailer length does not exceed 20 metres. The load can overhang the rear by up to 4 metres - measured from the axle. If it overhangs by more than 1 metre it must be flagged. At night red lights must be fitted to the rear. In daylight you should attach a fluorescent flag (white, red, orange or yellow), sized 400 x 300mm. A load can extend sideways up to 1.25 metres from the centre line of the trailer, but must be flagged if it extends more than 200mm beyond the sides. At night, you need to mark an extended load with white or amber lights to the front, red to the rear. a maximum gross vehicle mass (usually specified by the manufacturer) of 3,500 kilograms or less. (The gross vehicle mass includes the maximum load that the trailer can carry.)

Tyres -  All tyres must have 1.5mm of tread all round the circumference of the tyre and across atleast 75% of the tyre width.

Suspension types

There are usally 1 of 2 types of systems used on boat trailers. These are the very common leaf spring or torsional rubber. The coil spring system isnt used often as cant locate the axle both front and back and side to side.

Leaf spring -  this is used on all 3 types of axle systems. They are mounted on a pivot at the front and have either a shackle or sliper rear mounting to allow for hte lengthening of the spring as it deflects under the shock. One advantage of the leaf spring is that it can locate the axle both front and back and side to side. If on a tandem or triple axle trailer you will find a component called a compensator in between the 2 or 3 sets of leafs. This is there to transfer the load from one axle to the other when hitting bumps on the road.

 Torsional rubber - The most used and known type of this system would be the Duratorque type. The basic design has the axle housed in a tube with rubber elements around it. When you hit a bump on the road the rubber will absorb the shock which therefore is self damping.

Wheels and tyres

The tyres are a key part of towing your trailer safetly. All tyres must be fitted with crossply or radial tyres. The radial tyre has softer more flexible side walls and heavily braced tread area. The crossply has siffer side walls and less heavily braced tread area. When in use the radial tyre will give you much better grip, less tread distortion, longer life and redueced fuel consumption. The disadvantages though would be that the softer side walls take alot less strain to become damaged. For your own safety all the tyres should be the same on the trailer. The wheels for sale are almost always galvanised as they are cheap and great for preventing corrosion.

Couplings

Couplings are so important. You have to always check that when you purchase a car or trailer that you will be towing, always check the size of the towball compared to the coupling. Towballs will come in 2 differant sizes, either 1'7/8" or 50mm. The couplings themselves that are used on boat trailers can be put into 1 of 2 differant catagories:

- couplings for non braked trailers, to fit towballs

- couplings for braked trailers, "overide coupling" to fit towballs 

Couplings for non braked trailers, to fit towballs

These couplings are pretty simple. They are a basic handle mechanism that you lift up to fit over towball which is spring loaded so once placed over the towball the coupling will tighten up on it. There is a pic that you put through top of the coupling as a safety so the handle doesnt jump back up which will un-hitch your trailer from your veichle.

Couplings for braked trailers, "overide coupling" to fit towballs

This has abit more to it than the first coupling. These have the same sort of system for the handle and locking onto your tow ball but they also have a braking system which is apart of it. These brakes are operated by a piston in the coupling that when the trailer is pushed toward the car when under braking the piston will shorten which in hand pulls cables connected to the brakes and allows similar braking to the car. 

Brakes

 

Disc brakes

http://www.youtube.com/watch?v=rgbDyJhBb4c&feature=related a short video explaining how these brakes work.

Drum brakes

http://www.youtube.com/watch?v=bnc3VnQ8kUY another short video on the basic operation of this type of brakes.

Some basic and easy things you should do to keep your braking system well maintained. Firstly from time to time always check for and wear on the linings, shoes and pads. Check that none of the cables or linkages etc have corroded and still working fine. Always have your hydraulic fluid top up in the master cylinder. To keep ontop of all this you should regularly grease any moving parts and external linkages, cables and adjusters etc. 

Winches

You really have few choices when it comes to winches. A manual winch with either a cloth strip for smaller boats or a steal wire for larger boats or an electric winch. Unless your boat very large and heavy over 8m roughly you can get away with a basic hand winch. All winchs are mounted on a vertical post at the front of the trailer.

Lights

Depending on the size of your trailer and boat on it will depend on how many lights etc you will need as talked about in the WOF regulations. All boats though will have your basic braking and indicator lights on the rear of the trailer. You can get either your old common standard light that you can open up and change the bulb or the new style fully enclosed LED lights which will last longer and wopnt corrode. Above is the basic wiring diagram for the lights to be hooked up to your veichle.


referances:
www.google.com/images
www.wikipedia.com
www.voyagertrailers.co.nz
www.youtube.com
Unitec book (the bible)

Superyacht Ermis2

A UK naval architect company that design superyachts came to New Zealand to get there boat built. ERMIS2 can max out at around 55 knots

Fuel Injection part2

What does EFI stand for?
Electronic fuel ingnition

Who invented fuel injection and when?
Herbert Akroyd Stuart was the first to come up with the idea at the end of the 19th century and they were used on hot bulb engines. Which is an engine in which fuel is ignited by being brought into contact with a red hot metal surface inside a bulb. The first use of direct gasoline injection was on the Hesselman engine invented by Swedish engineer Jonas Hesselman in 1925. Hesselman engines use the ultra lean burn principle; fuel is injected toward the end of the compression stroke, then ignited with a spark plug.

Explanation of how the following components work....

Fuel rail

A fuel rail is essentially a pipe that looks like a rail. It is used to deliver fuel to individual injecters and designed to have a pocket or seat for each injector as well as an inlet for a fuel supply. They are benifical as it supplys a constant pressure of fuel which can be monitered by fuel pressure regulator.

Fuel pressure regulator
This component is used to keep the pressure of fuel in the fuel rail at a certain pressure. It is controlled by the diaphram so when there is to much pressure the extra fuel will be dumped back into the fuel tank. Here is a short video on how to test fuel pressure and looking at the regulator etc. http://www.youtube.com/watch?v=ERZe6Vrl7to

Idle air control (IAC)
An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars ECU receives information from various sensors and will output signals to adjust the idle air control motor in or out to adjust engine idle speed by controlling engine idle air.

Injectors
http://www.youtube.com/watch?v=eVCYR4B7IZ8&feature=related this video here is a basic video of the operation of the injectors. The fuel injector itself is just a high speed valve for fuel. Fuel injectors are normally fed power whenever the ignition key is on. The computer controls the ground of the circuit. When the ECU provides the injector with a ground, the circuit is completed and current is allowed to flow through the injector. This energizes an electromagnetic coil inside the injector, which pulls the pintle away from its seat. This makes it possible for fuel to flow through the injector and into the engine. When the computer removes the electrical ground to the injector, the electromagnetic coil becomes demagnetized and a spring forces the pintle shut to cut off fuel flow.

Lambda sensor (O2 sensor)
The use of the sensor is to help the engine run as efficiently as possible and also to produce as few emissions as possible. Its been worked out that there is a particular ratio of air and fuel that is "perfect" and that ratio is 14.7:1. If there is less air than this perfect ratio, then there will be fuel left over after combustion. ­Th­e oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage. The ECU looks at the voltage to determine if the mixture is rich or lean, and adjusts the amount of fuel entering the engine acordingley.

Manifold absolute presure sensor (MAP sensor)

The MAP sensor is a main input to the ECU. The MAP sensor measures the difference in air pressure between the intake manifold and atmospheric pressure which is provideding instantaneous manifold pressure information to the engines ECU.

Camshaft sensor and crankshaft sensor

The cam sensor tells the ECU which stroke number one piston is on so it knows which cylinder to fire or inject fuel into.The crank sensor can only send a signal telling the ECU that number one piston is at TDC but it cant tell it which stroke could be compression or exhaust.The cam position sensor on some common rail diesels only gives out a pulse while the engine is being cranked as once the ECU knows the position of number 1 piston and its reference point to cam position it shuts the cam sensor down as it doesn't need a reference signal to maintain the correct firing order.

Plenum chamber

It is located between the throttle body and the runners of an intake manifold, used to distribute the intake charge evenly and to enhance engine breathing.

Fuel Injection part1

Need to find out the purpose and how they work of the following components...

ECU - electronic control unit

The ECU is an electronic unit that controls all things electronic in your engine from how much fuel is being injected to ingnition timing. They are connected to all sensors such as ones below. It then absorbs all that information and makes the car run to the best of its ability with things such as fuel effinacy and firing times.


Mass air flow sensor?

Differant types of mass air flow sensors

This sensor is there to measure how much air is goin into the cylinder so that the ECU can then deliver the correct amount of fuel into the cylinder with the air. All these sensors have a built in intake air temputure senor which is also there to help work out an acurate reading of the mass air flow.


Air Temp sensor?
http://www.youtube.com/watch?v=dM4zUa9-Ib4&feature=fvwrel here is a video that describes the operation of  the Air Temp sensor. The purpose of an air temperature sensor is to help the computer calculate air density. A change in temperature changes the resistance in the sensor. Simply stated, the higher the air temperature gets the less dense the air becomes. As the air becomes less dense the computer knows that it needs to lessen the fuel flow.


TPS - throttle postion sensor?
http://www.youtube.com/watch?v=vyxNLrCMk3I here is a video the explains how a TPS works and a few of the advantages and disadvantages. This sensor is there to moniter the position of the throttle. the sensor is usally a potentiometer (three terminal resistor with a sliding contact which creates a adjustable voltage divider) which provides a variable resistance depending on the position of the valve.

 

Throttle body?

In older engines the throttle body is the body of the carb which has all the air flow go through. In fuel injected engines it is part of the air intake system which controls the amount of air going into your engine.

Carburetor

The components of a basic carb....

How does a carb work?
A carb is the component that mixes the air and fuel together before entering the cylinder to the correct amount so the enigine will fire. The air and fuel are brought into the carb at differant points. Air which is being sucked through the carb is caused by the low atmospheric pressure in the cylinder which causes the air to be pulled from outside the engine. The fuel enters through a jet in the centre of the venturi which is also dependent on the amount of atmospheric pressure inside the carb which is all controlled by the amount of throttle that is being used or how far the throttle butterfly is open. This is a video with a basic explanation: http://www.youtube.com/watch?v=zUuVQfvWSnI

What are the holes in the emulsion tube for and how does it work?
The emulsion tube is a main jet with holes in it. It is used to keep the air fuel mix ratio more uniform as the throttle butterfly is opened.

What is the purpose of the float in the carb?
The float is situated in a chamber where the fuel is pump into from the fuel tank where it will be before getting sucked into the venturi of your carb. Its main purpose is to keep a constant fuel level inside the chamber. It needs to have a constant level as if there is to much fuel your engine will run rich and to little the engine will run lean.

How does the manual choke and automatic choke work?
http://www.youtube.com/watch?v=k-SxQzvCw3U a quick viedo on a thermostatic auto choke.
There are two ways these automatic chokes can be operated: by the heat of the cooling system or exhaust or by the heating effect of and electric current. When your engine is cold there is a bimetal spring situated in the carb connected to the choke butterfly which is wound up tightly which is holding the butterly closed. Once there is heat from either type, the spring will slowly unwind until the buttterfly is open. A manual choke is a lever connected to the choke shaft that has the butterfly on it and when you pull or push the lever it will open and close the butterfly.

Vaccum fuel pump

How does a vacuum fuel pump work on a two stroke engine?
The vaccum fuel pump is bolted to the crankcase of your 2 stroke which is connected to all your carbs individually. It works on the effects of atmospehric pressure inside the cylinder. The diaphram inside the pump will be pulled open from the pressure created in the cylinder which will cause it to open the inlet jet for fuel to enter the fuel chamber which also will create atmospehric pressure in the supply line that will pull the fuel up to the pump from the tank. When trying to crank your engine over these pumps have very low pumping pressure so you need to have a prime buld in the supply line which you manually pump to fill the carb only for starting.

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mechanical lift pump

What is the purpose and how does mechanical lift pump work?
The purpose of a mechanical fuel pump is to pump gas from the fuel tank to the carb. This type of pump has a lever that is hitting one of the lobes on your camshaft. This lever will go up and down as it hits the lobe causing a vaccum effect with the diaphram. This causing a low pressure in the supply line which causes fuel to be drawn up from the fuel tank.

What pressures would you get from these types of pump?
2 - 5 PSI

What does S.I mean?
Spark ignition - petrol  where the initiation of the combustion process of the air-fuel mixture is ignited within the combustion chamber by a spark from a spark plug.

What does C.I mean?
Compression ignition - diesel uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber.

What is the four stroke cycle?
-intake
-compression
-power
-exhaust

How does a bimetallic spring work in a automatic choke work?
The bimetallic spring is a temputure sensitive spring that is attached to the choke butterfly. When the spring heats up the spring will unwind which in turn opens the choke. This video show the spring being heated up and unwinding. http://www.youtube.com/watch?v=7suzzg1kZgY. The bimetal spring may be located in a well in the intake manifold where it is heated by exhaust gases flowing through the crossover passage, or it may be located inside a plastic housing on the carburetor itself.
The choke housing may be heated one of three ways: by hot air siphoned up through a pipe in the exhaust manifold that then flows through the housing and enters the carburetor, by an electrically heated element inside the housing, or by engine coolant circulating through a hose attached to the housing.

What is the purpose of the venturi and how does it work?

The venturi is where the air and fuel mix mets in the carburetor. The start of the venturi is alot wider than the centre of it as the picture too the left shows. When the airflow from the atmosphere rushes through the carb it is forced to speed up as the venturis width gets smaller. This creates a low pressure where the fuel now enters the carb and mixes with the air.


How is the idle and mixture screw adjusted?
This screw adjusts the throttle butterfly position at idle which in turn raises or lowers the engines RPM. It does not control the air fuel ratio. When you are adjusting it you will turn the screw clockwise to open the throttle butterfly if the revs are to low and the oppisite if the revs are to manufacturers specs.


How do you adjust the float in the carburetor?

To adjust the float you will need to firstly take the carb off the intake system and dismantle so you can access the float in its chamber. If you turn the chamber upside down with the float still in there it will hold the float where the full will hold it when the chamber is full of fuel. You should check the gap between the metal bracket and the top of the float againest manufactures specs. If adjustment needed you will just need to bend the bracket until sitting correctly.


An engine lacks power. What is the likely problem?
There are many differant resons an engine will be lacking power but to do with the carb there is only a few differant things that can cause this. Firstly if any of the fuel jets are blocked you will lack power as the fuel air mix will be to lean. Also if the air isnt sufficent the mix will also be too lean.

Explain how a fuel cut off solenoid is checked and why is it fitted?

This solenoid is fitted to stop the flow of fuel once the ignition has been turned off. When the ignition is turned on the solenoid will open the fuel passage so fuel can get to the engine. Once the ignition is turned off the solenoid loses power and shuts this passage. To check them you need to put power to it and if itll open its working fine.

When dismantling a carb what precaution should you take?
First of all always take note of where everything came from and always mark things that should be marked such as the way the housings go together etc. Never turn the carb upside down if your not fully dismantling it. and make sure your work area is always tidy as carbs have very samll components which can be lost easily.

referances:
www.google.com/images
www.wikipedia.com
www.howstuffworks.com
Ed May books Vol 1 & 2

Health and Safety part2

Gas welding is a part of marine engineering which requires a greater knowledge in the health and safety with the equipment you are using as it involves bottles of highly pressurised gases and open flames. You always need to check your work area before you start welding to check where everything is such as fire extinguishers, the main gas cut off valve (if you aren't working straight off the bottles) and cold water taps incase of burning yourself on hot metal or the flame.

There are two cylinders involved one has oxygen and the other has acetylene. It is a worldwide requirement that they are colour coded. Oxygen-black Acetylene-red/maroon. When transporting and using the acetylene it must always be in an upright position secured but the oxygen doesnt need to be upright, still secured though.

Always check cylinders and valves for leakage and hoses for cracks, burns or and other damage

As you can see the hoses coming off the acetylene bottle are also red. With the oxygen the hoses are blue as a general rule which makes it easier to know which hoses goes to what bottle. It has also been designed so you can never put the hoses, gauges etc on the wrong bottles as the thread is oppisites for each bottle. The oxygen bottles and the other hardware are all fitted with right hand thread and the acetylene gear is all left hand thread for safety purposes. The max fill pressure for a oxygen bottle is 2500psi and acetylene is alot less at 225psi with a max working pressure of around 15psi.

A few quick videos about welding and safety:

http://www.youtube.com/watch?v=VfRQxxxLJuo

http://www.youtube.com/user/TheAtHomeWelder#p/u/24/FG3io6OCUr8

If you are putting the pressure regulating valve and gauges onto the gas bottle never put oil or grease on or around any threads as this could cause spontaneous combustion. When you have finished welding for a period of time, at all times your line pressure should show 0psi and the pressure regulating valve should be closed incase the bottle is leaking. This will prevent gas or oxygen leaking through the lines and into your work place.

The torch is where the gases are mixed together to form the working gas. As for the rest of the equipment this is no differant with the colour coded valve controls. Always check the torch is all together properly before you try light it up as this could cause injury to yourself. When igniting the torch always face away from you and prefrably towards an extraction unit. When it comes to the tip there is many differant shapes and sizes for diffaerant heats so be sure you have the correct one for the job your wanting to do. Always check the tip is clean and clear of any metal in or on the end of the tip as this will affect your flame and could catch you out. Flashback arrestors are there to prevent and flame burning back up into the equipment causing damage or explosions. If in the case of a flashback happening you just need to pull the cap which resets it and you can weld again.

 

Flashback arrestors are there to prevent and flame burning back up into the equipment causing damage or explosions. If in the case of a flashback happening you just need to pull the cap which resets it and you can weld again.

referances:

www.google.com/images

Health and Safety part1

Health and safety starts with yourself and being aware of hazards and your surroundings. Also having a clean work enviroment is key to a safe workplace. The moment you set foot in to a workshop you need to be prepared and dress apropriately which means having the right safety gear on. This involves wearing steel toe boots, cotton or non flamable overalls and having things like earmuffs, safety glasses and gloves close by if necessary. Another key point is always be familiar with the tools and machinery you are using and if not dont be afraid to ask someone.

With all this safety gear there is differant levels of protection from all parts so you need to be sure you have the correct sort of gear for the application. Few examples would be - the safety goggles will be differant shades of lenses as a darker tint will be used for things like welding and the clear lenses will be used for things like using a lathe, bench grinder etc. 

Knowing the use for each type of fire extinguisher is another part of being safe in your work place. If you were to use the wrong extinguisher it could have terible concequences for example if you were to use a water-based extinguiser in or near an electrical fire the user could get electrocuted. Below is a table to explain what you can and cant use each extinguisher for.

When it comes to tooling and machinery you will always need to be aware of what you are using and how you are using it. With the hand tools they are only made for specific applications so dont use them for other reasons for example dont use a file for a hammer as the file will lose its shape and grit. If you use them correctly this will keep your hands and fingers out of the way and will prevent them getting hurt.

With the machinery there is alot to remeber to keep yourself safe and to continue to work. The similar things to remember from machine to machine is basic things like take note of where the emergancy stop button is also make sure the machine is clear and clear of clutter incase anythning does go wrong.



Safety goggles must always be worn while operating this machine, make sure it is clean of all metal fillings so what you are working on can sit level under the drill piece, always drill slowly to save the drill bit biting into your material, use oil to lubricate the drill bit if nessacary, use gaurds if supplied and able to be used, remove chuck before drilling



once again make sure your material is locked in so it doesnt move and hurt you, wear safety glasses so there is no chance the metal filings getting in your eye

Always wear safety goggles when using this machine, check wheels for any cracks or dents that could catch your material while grinding, have a pot of water near so you can cool down your work while working as it will get hot fast, use gaurds where your able to as extra protection for your eyes



Safety goggles must always be worn as there is alot of metal filings around, before operating remove chuck, keep hands clear of all rotating parts, do not wear any baggy clothing around this machine as you dont want it to get caught.

The health and safety of all workers is down to themselves understanding their workplace and its enviroment.

referances:

www.google.com/images - images