granddaddylow:
I was sent out with an 18.65m trailer the other day. Went well enough once I worked out that there was a button to lock the rear steer axle for the purposes of reversing.But how does the rear steer axle decide on the angle to steer at? I’m sure it isn’t taking the steering angle from the unit because that wouldn’t be useful. Does it calculate it based on the angle of the 5th wheel to the trailer?
This is called a selftracking axle, makes it easier to go into tight spots, and for reversing you need to block the axle, sometimes there’s a switch on the dashboard for that, most of the times it’s switched to your reverve gear.
The most common system used on stepframe trailers used for STGO CAT 1 work, as it doesn’t require all that more maintenance and it saves on weight.
Hydraulic steering works as Toonsy said, there’s a wedge that goes into the fifth wheel and that’s coupled to a turntable, hydraulic connections attached to the axles and the axles can be steered seperataly by remote control. Great system, until there’s a leak in the system. Once you’re used to it, you’ll never want to go back to trailers with fixed axles.