Truck Shop
Senior Member
One item I have never seen posted on here is raising a truck with air ride trailer connected. For those who
haven't experienced what happens when the steer axle is jacked and a stand under it with trailer hitched to fifth wheel.
If only the yellow tractor valve is pulled and the red trailer valve is in {brakes not set on trailer} and the air ride
height valve is not plumbed to a emergency tank to keep air in suspension air bags when air is dumped or air
bleeds off the trailer will creep forward as it sinks down. Also pushing the tractor with park brakes set forward.
It can and has pushed steer axles off the jack and tipped the stand-if one was used. Some trailers come with
swing down stiff leg that swings into place on axle air bag saddle when air is emergency/red valve is pulled
to stop trailer from sinking down but most trailers with air ride don't have it. A loaded trailer sinking down
can push the tractor ahead 3 plus inches and shove it right off a jack. Very dangerous so always pull both valves
to be safe.
haven't experienced what happens when the steer axle is jacked and a stand under it with trailer hitched to fifth wheel.
If only the yellow tractor valve is pulled and the red trailer valve is in {brakes not set on trailer} and the air ride
height valve is not plumbed to a emergency tank to keep air in suspension air bags when air is dumped or air
bleeds off the trailer will creep forward as it sinks down. Also pushing the tractor with park brakes set forward.
It can and has pushed steer axles off the jack and tipped the stand-if one was used. Some trailers come with
swing down stiff leg that swings into place on axle air bag saddle when air is emergency/red valve is pulled
to stop trailer from sinking down but most trailers with air ride don't have it. A loaded trailer sinking down
can push the tractor ahead 3 plus inches and shove it right off a jack. Very dangerous so always pull both valves
to be safe.