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Rubber Torsion Axle Suspension
Except for periodic inspection of the fasteners used to attach the rubber torsion axle to the trailer frame and a visual
inspection of the welds, no other suspension maintenance is required. However, all maintenance regarding hubs, drums,
rotors, bearing, wheels, and tires, should be adhered to.
The torsion suspension system is a self-contained suspension
system that is housed entirely inside the axle beam. Unlike a
spring suspension system, the axle beam attaches directly to the
trailer frame without the need for various mounting components.
The action provided by the rubber torsion axle provides several
operating advantages (over leaf spring suspension) including
independent suspension for each wheel and a maintenance-free
design.
How the Rubber Torsion Suspension System Works
The rubber torsion axles provide a much improved trailer
ride relative to conventional spring axles through a unique
arrangement of the steel torsion bar surrounded by four nat-
ural rubber cords encased in the main structural member of
the axle beam. The wheel/hub spindle is attached to a lever,
called the torsion arm assembly. This assembly includes the
torsion arm, the torsion bar and spindle. As load is applied
to the trailer, the torsion arm assembly pivots around the tor-
sion bar, causing a rolling or compressive resistance in the
rubber cords inside of the axle beam. Both sides of the axle
are completely independent from one another.
Direction of Travel
The rubber torsion axle beams and stub axles must be
mounted with the torsion arm and spindle trailing to the rear
of the axle beam.
As Load is Applied to the Trailer, the Torsion
Arm Moves to Absorb the Shock
Wheels and Tires
Wheel Selection
Wheels are a critical component of your running gear system. When specifying or replacing your trailer wheels it is
important that the wheels, tires, and axle are properly matched. The following characteristics are extremely important
and should be thoroughly checked when replacement wheels are considered.
1. Bolt Circle. Many bolt circle dimensions are available and some vary by so little that it might be possible to attach
an improper wheel that does not match the hub. Be sure to match you wheel to the hub.
2. Capacity. Make sure that the wheels have enough load carrying capacity and pressure rating to match the maxi-
mum load of the tire and trailer.
3. Offset. This refers to the relationship of the centerline of the tire to the hub face of the axle. Care should be taken to
match any replacement wheel with the same offset wheel as originally equipped. Failure to match offset can result
in reducing the load carrying capacity of your axle.
Torque Requirements
It is extremely important to apply and maintain proper wheel mounting torque on your trailer axle. Torque wrenches
are the best method to ensure the proper amount of torque is being applied to a fastener.
It is important that the specified torque levels are maintained on the wheel nuts or bolts on your axle to prevent loose
wheels, broken wheel studs, and possible wheel separation from the axle.
Wheel nuts and bolts are offered in different cone angles (usually 60° or 90°). It is important to match the angle of the
fastener to the wheel on the axle.
