Servicing your Trailer.
Servicing your trailer regularly will safe you not only money but probably a lot of grief. Many people use their trailer without giving it any thought. Until of course it lets them down, usually at a really important time. So with this article to guide you why not give your trailer a service?
Before we start you need to understand that your trailer must be in a roadworthy state. Just as a vehicle meets the MOT standard, your trailer also meet that same level of condition. In otherwords, the tyres, brakes, lights and number plate should be legal. The condition of the framework and body of the trailer must be sound, with nothing hanging off or loose.
The trailer's lighting board must have a device that sounds or flashes in unision with the indicators. Any trailer over 750kg gross weight or over half the weight of the tow vehicle must be braked. The maximum speed with a trailer is 50mph on single carriageways - unless the speed limit is less than this - and 60mph on dual carriageways and motorways.
Remember that trailers are not allowed in the outside lane of a motorway. The number plate on the trailer must match the towing vehicle! You often see different number plates on car and trailer!
Tyres are subject to the same laws as a car for depth and cuts and red triangular reflectors must be fitted at the rear of the trailer. Side orange reflectors must be fitted to trailers over 5m (15ft) long and white front marker lights have to be fitted if it’s over 1.6m wide or over 2.3m body length. When you get your trailer out for maintenance, start at the front and work to the back methodically or use a checklist.
Electrics
Check the cable for pinching damage from the brake or jockey wheel. When connected up if all lights glow faintly, this usually means a poor earth connection. Try spraying with WD40 or similar to prevent further dampness affecting the plug. If you intend changing the lights, try rubber lights as fitted to Indespension trailers and HGVs or, my preference, Land Rover round rear lights and indicators, which are cheap and easily sourced. Test all lights work properly.
Coupling
On braked trailers check whether the coupling head tube is straight. If it is bent in any direction, you will need to replace it as it will prevent the brakes working properly. Move the coupling head; if there is any movement between the slides, grease the two nipples with a grease gun. If there is any back and forward movement, this indicates the gas damper has failed. However, it is fairly easily replaced.
Unbolt the coupling head and nut at the rear of the coupling, and the damper will slide out the front of the coupling tube. A trailer or caravan dealer will be able to match up the part numbers on it. Check all around the coupling body for cracks. If yours is cast iron and it has cracks, scrap it.
Check the chassis for cracks, especially on any welds and where the suspension bolts on. Brake-away cables must be fitted to all braked trailers to pull the brake on if the coupling or tow ball fails. It is illegal to attach it to the towball, it must be attached to a separate part of the towbar or vehicle.
Brakes and bearings
If you wish just to check the wheel bearings: chock the trailer, jack it up and grasp the rim. move the wheel in all directions. It should just about have a slight movement that you can feel; none at all and its too tight, any that’s visible is too loose. Remove the centre grease cap, (you don’t have to remove the wheel) and adjust the castellated nut to achieve the desired clearance, one groove at a time. Replace any damaged split pins.
If you wish to check your brake condition, loosen the wheelnuts, jack up the trailer and remove the wheel. Place a box underneath. Remove the grease cap and castellated nut, and hook out the outer bearing. Put it somewhere clean. Use a rubber mallet and tap around the brake drum to loosen it - remember to let off the handbrake. If it is stubborn you may have to back off the brake adjusters (usually a 17mm socket on the backplate). Remove the drum, being careful not to get any dirt in the bearing surfaces. Inspect the brake lining thickness; these must be replaced when down to 0.5mm at the lowest level on the shoe or above the rivets.
Removing the shoes is easy, unhook the springs and they will come off. Getting them back on is far more difficult. Remember where the springs hooked, draw a picture or take a photo. Make a decent hooked tool with a handle to get a good grip on the spring end to hook them back on.
Put everything back together packing the bearing with grease and keeping it all clean. Refit the wheel and adjust the bearing as above, leaving the grease cap till last.
Adjusting the brakes
Make sure the brakes are fully off, tap the nutted ends of the brake cable near the brake equaliser under the centre
of the trailer with a hammer to be fully sure. Spin the wheel, adjust the brake adjuster on the rear of the backplate (usually 17mm) until the wheel locks up, them back off slowly until the wheel frees up.
Repeat the procedure fully if necessary to get it right, don’t just tighten it a bit if you feel its too loose, as the brakes settle after they’ve been refitted, and it may be worth doing each side a couple of times alternately. Once both sides are done, apply the handbrake sharply several times, then make sure they are fully off using a hammer as above, and check adjustment again.
Brakes with the adjuster backed too far off (too loose) can cause the brakes to jam on, or to brake unevenly causing snaking. Grease the exposed ends of the brake cable and any grease nipples fitted to the cables themselves. On most trailers with over-run cable operated brakes, there should be a 10mm play
between the arm that operates the rod to the cables, and the rear of the coupling tube.
Once you have completed all the jobs mentioned above, you will be far more confident taking your trailer on journeys. You will also have a better understanding of how your trailer is constructed. This knowledge will benefit you when it is time to change trailers and buy your next one!