Air Couplings & Sliding Axles

Okay just want to clear up a question I got off Neil this morning about air couplings and sliding axles on trailers.

The coupling picture shows what we use over here.

With the trailer sliding axles, the pic shows the older type, the handle pulls out the locking pins and (with the trailer brake set) you slowly shunt forward or backwards to slide the trailer box over the axle group therefore changing the distance in relation to the king pin.

"Why on earth would i want to do that?????" i hear you muttering.

Well it for 2 main reasons.

1. You have maximum axle weights on each axle group (steers, drives and trailer) if you are too heavy on your trailer, you can slide your trailer axles back and it will lighten the load on the trailer but make your drives a bit heavier, note you can also move your 5th wheel so you can also alter the weight distribution between your drives and your steers. Notice on the pic the holes that the pins lock into, each hole makes the difference of about 500lbs.

2. Axle distance compliance. Each State & Province has its own rules and regs about the distance of the trailer axle group from the king pin or the drives. Bearing in mind you could be passing thru a few different jurisdictions, you have to be legal where ever you are, sometimes it means adjusting axles on route. The pic shows an older trailer with a manual handle to disengage the locking pins, the new ones have a little air operated button located roughly in the same spot which is a little easier.

The first few times you have to move the axles it can be a pain and sometimes on the older ones the pins need a little persuading with a hammer. The first time i had to do it, it took about 20 mins and a lot of sweating and cursing, now it takes about a minute. Most of the factories we go to require you to slide you axles to the rear anyway as it lifts the rear up to the same height as the door (read bay or ramp) over here we dont have adjustable height on the trailers.

"Where on earth do i get a hammer from" i can hear you ask.

Well the answer is $20 from Canadian Tire. Seriously you need to carry a hammer anyway to check tire pressures, dont laugh, i had never heared of that either but it makes perfect sense. When you are checking a vehicle over you give the double tires a whack and you instantly know if one is flat.