TRAILERS # 2

HYDROLIC BRAKES
The hydrolic system for braking is used for drum brakes and disk brakes, disk brakes are more efficient because they don't hold sea water like drum brakes.
CABLE BRAKES
Another method of braking is cable braking - this works by the same medthod as a hand brake on your car. it is not as efficient as the hydrolic system becuase the brakes can only be used when the trailer is stationary or un-hitched.
Both types of brakes are available in drum and disk brakes, disk brakes are more expencive but are more effective and don,t need as much up-keep.

WHEELS & TIRES

• Dont ever be tempted to put car tires on a trailer this is because trailer tires hav much stonger side walls than ordanary car tires this is because - trailers have to suport more weight, under constant threat of damage whilst driving e.g. being kerbed etc, and sunlight/heat starts to perrish the rubber.
• On the sidewalls of trailer tires informs you that: the max load limits for the tires are ####. If there are two tires rated for 250kgs each, then the total weight on the trailer and the boat and gear--should be no more than 500 kgs for example.
• When possible keep tires out of the sun e.g. in a garage or storage unit.

HUBS & BEARINGS

• Most new trailers usually have bearing protectors. These are metal caps with springs that hold grease under pressure which stops water entering and corroding the bearing. If your trailer doesn’t have protectors, they can be be added to the hub. They are easy to fit to the hub and aren't verry expensive.
• There are a range of different hubs for trailers all with multipul stud patterns and sizes, so keep in mind that when/if you are buying a new wheel to pick out the right size for the hub.
• On boat trailers the hubs are galvanised and hardened, if you are building a boat trailer make sure you get the hubs galvanised to avoid replacing them so soon as a result of rust.

COUPLINGS

• The most common type of coupling is the simple ball and socket, found on most cars, there are diferent types of couplings though according to the size of the boat and trailer e.g.hydrolicaly  (serge) braking coupling, cable braking coupling or basic non braked style. You can also get couplings that have a head that swivels which allows you to attach the trailer from an angle.
• If you have a bigger boat that needs to be towed by a bigger vehicle e.g. a truck you would have a different coupling on the trailer (these however are not so common).

WINCHES

• Generaly your winch should be rated to pull at least half the combined weight of your boat, motor and gear. Every so often you should check your winch for loose mounting bolts and parts within the winch housing.
• If you use an electric winch (usualy only on flash or big boats to big to winch up manualy), check that the power cord is in good condition and that there is no corrosion on the wire because you might over heat the winch if the current isn't making it to the winch cleanly (not 100%). Make sure your winch line doesn't rub up against anything while loading/unloading the boat. Check the line frequently for wear or fraying (the line could be a steel cable or a thick strop). Even a small amount of fraying or wear can significantly reduce the strenght of the cable/strop.

LIGHTS

• L.E.D - efficient when it comes to power but power is not important when the car is running.
• Normal light bulbs are just as bright as L.E.Ds (plural)
• The casings of the lights need to be water proof or removable.
• Do not submerse the plug next to the coupling
• The best wire to use is strannded copper wire because it is flexable and break resistant.

W.O.F REGULATIONS

•  
  • You can't travel more than 90km/h when towing trailers or other vehicles on the open road. You can only travel at this speed if you have a rigid connection between the vehicles.
  • If you have a non-rigid connection between the vehicles (like a rope) you cannot exceed 50km/h on any road.
  • Don't tow a trailer or another vehicle at the maximum speed unless you're sure you can do so comfortably and safely.
  • Leave at least a four-second gap between you and the vehicle ahead - even more in bad weather. The extra weight you're towing can dramatically affect your ability to slow down and stop.
  Leave at least a four-second gap between you and the vehicle ahead
  • Slow down before curves and avoid braking suddenly - especially on gravel or greasy roads. Use a lower gear when travelling downhill.
  • Don't overload your trailer as this will affect its stability and control at any speed.

LINKS I USED

• http://www.nzta.govt.nz/vehicle/your/motorhomes.html
• http://www.pickyguide.com/sports_and_recreation/boat_trailers_guide.html
• http://www.boatus.org/onlinecourse/reviewpages/boatusf/project/info3c.htm
• http://www.ehow.com/list_7486041_boat-trailer-specifications.html
• http://www.synthx.com/articles/trailer-versatility.html

TRAILERS

TRAILER MATERIALS

• Galvanized steel - trailers have galvanized steel skeletons. This type of framing is the most solid way of making boat trailers. They also offer the best protection in the brake lines and the wiring systems (if the steel is enclosed e.g. box section or tubing).
• Aluminium - trailers are made of high quality aluminium alloy so are therefore very light compared to the other option of steel. Aluminium trailers are strong, but they don’t have the durability of a steel trailer. Aluminium however wouldn’t rust as much as steel. You can also galvanise aluminium for added rust protection.
• Steel – trailers have the same structural qualities as the galvanised steel trailers apart from the corrosion
• Alot of manufacturers give the customer a choice of galvanized steel or painted steel trailers. The painted trailers are ideal for freshwater but are vulnerable to rust in saltwater, Galvanized trailers cost more, but it means less maintenance, especially if they will be reversed into saltwater.

TYPES OF CONSTRUCTION METAL

• The best type of steel to use on a boat  trailer would be an enclosed type of shape e.g. tube or box section, this is because you can run your light wires etc. inside the steel so it is protected from impact from all sides, weather (sun perishing cables) and salt water if the trailer is built with drainage holes at the lowest points. It is important however that even with an enclosed cable space and drainage holes that the wiresneed to be properly insulated.
• If you decide to build a trailerusing I-beam or C-channel Iwould recommend using steel then spending that littlebit extra to get it galvanised. This is because an aluminium alloy trailer built out of I-beam or C-channel is not strong enough.

TYPES OF TRAILERS

• Single axle - trailers with a single axle are much easier to manoeuvre by tow vehicle or by person, the downside to a single axle boat trailer is that at high speed there is more chance of it fish tailing from behind the car than a tandem axle trailer, it is also more important for a boat to be in the right position over the apex on a single axle trailer compared to a double because there is more support on 4 wheels rather than 2.
• Roll-on trailers, also known as Roller style trailers, uses rubber and or polyurethane rollers for ease of launching and loading the boat without submersing the trailer very far in the water. 
• Glidepath trailers, also known as a Float-on style trailers allow the boat to float onto the trailer. This is made possible because the trailer gets driven so it as submerged to about 3/4 of the trailer is under water.
• Pros - The roller trailer - you don’t have to drive the boat so far into the water to get the boat onto the trailer, and the rollers them selves make the winches job much easier. The guidepath trailer means that there is hardly any effort to get the boat onto the trailer because the water has all the weight.
• Cons – roller - saltwater eats away at the bearings on the rollers which causes the rollers to seize and the winch therefore is put under more strain because it is having to drag the boat over the rollers.
• Guidepath - because the trailer is being almost fully submerged in the salt water there is more chance it would rust.
• When choosing the trailer you have to take into account where you will be launching the boat e.g. is there a drop off at the end of the boat ramp, if so the roller trailer is the better choice because you don't have to drive it into the water so far.

OVERALL DIMENSIONS & RULES

• If you own a boat you can tow a trailer that can be 2.5m wide, up to 4.25m high when the boat is sitting on the trailer, and 11.5m long, assuming that the car plus the boat doesn't exceed 20m which is the limit.
• When you load your trailer the I deal position is to have the weight is so about 10% of the weight is taken on the tow ball and the rest supported and distributed over the single/tandem axles of the trailer. If there is to much weight on the tow ball the trailer coupling will not be parallel to the ground therefore the car will be hard to steer (and good luck pulling your boat up a steep launch ramp if the car is front wheel drive). If the load is to far to the back of the trailer  it will have the tendency to fish tail around at certain speeds.
• Another thing to consider is what gear you have in the boat, “is it heavy” if so where is the weight adding to the load.
• The tongue of the trailer is also very important – the A-frame design has the coupling of the trailer where the apex of the frame meets.
• The draw bar style has a strut running through the apex of the A - frame which extends out futher and is attached to the towbar by a coupling.

SUSPENSION TYPES

Leaf springs single axle

• Advantages :  This is the most common type of suspension and probably the most used for boat trailers.  They minimize stress on the frame because  it distributes the load over 4 equal points on the frame.  They are easy to set-up so the axle position is correct according to the main frame of the trailer.  They are attached with through bolts for simple constraints of the system, and the back shackle is a simple, dynamically stable method of taking up spring deflection.
• Disadvantages : include size, weight, and package constraints (they can take a lot of room under the trailer and limit how low the bed can be made.

Multiple Axle Leaf Springs

• Advantages :  Mostly the same as above, but for multiple axles, these springs distribute a simple load fairly well to 8 points on the frame instead of 4.  These can be made to load share quite well with a rocker link (usually included).
• Disadvantages :  Like above on the single axle, these take a lot of space and make limitations on trailer bed height.  Different variations exist, but typically for load sharing the rear axle is not as well constrained as the front, so these tend to be somewhat less stable than the simple single axle.

Coil springs on trailers are less common because they are bouncey which could unsettle the boat, coil sprins are also a mission to set up because you have to attach torsion bars for stability.
Overall leaf spring suspensinion is more practicle all round and better for boat trailers because the boat wil be on rollers or guidepaths the height of the bed is not a big factor.

WEIGHT LIMITS FOR BOAT TRAILERS

If the load on the trailer adds up tomore than 2000 kgs it has to have a braking system, this mostly applys to single axle trailers because dual axle trailers usually have a breaking system anyway.

Trailer Weight Estimates
This chart relates to single axle trailers only
Trailer Capacity	No. Axles	Trailer Length	Trailer Width	Weight
1000 lbs.	1	15'4"	62"	295 lbs.
1500 lbs.	1	15'4"	62"	305 lbs.
2000 lbs.	1	17'2"	88"	492 lbs.
2450 lbs.	1	18'2"	96"	522 lbs.
2999 lbs.	1	18'2"	96"	625 lbs.
3500 lbs.	1	19'8"	96"	677 lbs.
5000 lbs.	1	20'8"	96"	933 lbs.
7000 lbs.	1	27'9"	96"	1512 lbs.

BRAKES
Most trailer braking systems are either cable or hydrolicly opperated.
HYDROLIC - Also know as serge braking system, this in my oppinion is the most effective and economical form of trailer braking because it significantly reduces the wear and tear on the axles and wheels, this is because the brakes are being used even whilst driving (only when slowing down).