how does the lazy axle work??

[Romell R]

Hey fellas another question for ya. Does anyone have or know of illistrations of how a lazy axle is setup on the chassis of a truck? and how it works? thx in advance for any help that can be provided.

[mountaindewd]

Romell,

By lazy axle, do you mean lift axle(pushers and tags)?

If so, you can Google "lift axle" and see how they are constructed. There are many variations in design from different manufacturers. Basically, they usually have 2 small air bags situated in the design that inflate with the control inside the truck lifting the axle/tires off the ground. Deflating those and inflating the suspension air bags will lower it to operating position.

If you are looking to get one for your build, GWtrucks, sold through sourkrauts, has a nice, multipiece unit in resin. You can also contact Gary at GWtrucks directly here. gwtrucks@yahoo.com

[QCDOC]

Dead Axle

[Semi Trailer Mechanic]

Romell

For the most part Les is correct. On some there are two bags per side a small one up towards the hanger and a larger one directly over the axle as the main air bag inflates that pushes the axle down taking weight off the steering axle and the two drives. The smaller air bag up by the hanger will be deflated. As the main bag deflates the air escapes out the exhaust port of a solinoid valve. At the same time the smaller air bag inflates pushing the front of the trailing arm causing the axle to lift on a pivot.

There are air regulators that control the amount of pressure exerted on the axle. Here's a problem I had to correct in the past. The regulator failed and too much pressure was on the two axles on a quad axle East dump trailer. Loaded there wasn't a problem. For some reason when the driver dumped (contaminated soil) he didn't raise the two lift axles and the two rear ridged axles were barely touching the ground. When the driver hit the brakes w/ the trailer hand brake those rear axles locked up.

There are a few different configs.

1 A non steer axle w/ dauls basically a trailer axle.

2 A steerable. Which is alot like a steering axle. This has a tie rod/cross shaft. The difference between that and a steering axle is there are coil-over shocks the bolt to the spindel and the axle. The pressure of the shocks on both sides keep the wheels straight. As the truck turns the drag steers it. After the truck has completed the turn the pressure from the shocks straightens it back out. Drivers say that when a coil over shock fails the truck feels like it will flip over. I can tell you from experience it's not fun trying to compress those shock to install them.

3 Strong arm which is an axle mounted to a frame that's attatched to the rear of a dump trailer or dump truck mixer and so on. This is raised when not in use

Pusher refers to a truck where the lift axle is in front of the drive (s)

Puller refers to a truck where the lift axle is behind the drive (s)

Edited September 2, 2010 by Semi Trailer Mechanic

[Romell R]

Thx guys for all this great info