Trailer Suspension Types

The suspension systems incorporated into Cerka axles are designed to provide the trailer owner three basic functions:

1. Attach the axle to the trailer
2. Dampen the effects of road shock
3. Provide stability to the trailer

All Cerka suspension systems are available in single and multiple axle configurations. 

Double Eye Leaf Trailer Springs

Double eye springs have eyes formed in each end of the spring and are attached to the trailer as follows:

1. The front spring eye is attached directly to the front hanger with at bolt and nut.
2. The rear spring eye is attached to  a pair of shackle links which are attached to either a rear hanger (in the case of single axle installation), or an equalizer (in the case of a tandem axle installation).
3. For triple installation, the middle axle is towed by equalize eye attachment.

The articulation of this suspension occurs when the spring becomes loaded and consequently lengthens.  The double pivot action of the shackle links accommodates this articulation and allows the system to move freely.

In multiple axle installations the action is the same but with the additional movement of the equalizer assembly which serves to transfer instantaneous loads from one axle to another in an effort to "equalize" the load between the axles.

Grease lubricated Suspension Bushings

In the optional heavy duty attaching parts kits, the suspension bolts and equalizers have grease zerks which provide a lubrication path to the bronze bushing located in the spring eyes and equalizer.  These parts should be periodically lubricated and inspected for signs of excessive wear, cracking, or hole elongation.  If excessive wear, cracking, or hole elongation exists, all links and worn parts should be immediately replaced.

Slipper Leaf Trailer Springs

Slipper springs have an eye formed in one end only with the other end formed into a reverse curve.  The attachment of these springs is a follows:

1. The front eye is attached directly into the front hanger with a bolt and nut.
2. The rear end of the spring is captured in the rear hanger or equalizer with a "keeper bolt" that prevents the spring from coming out when the trailer is jacked up for service.

The articulation of this suspension occurs when the rear end of each slipper spring slides against the wear surfaces provided in the rear hangers or equalizers.  This suspension is also available in single and multiple axle configurations.

Note: Failure to do proper and periodic maintenance of these important structural parts may result in sever and catastrophic damage or injury to property.

Torflex Trailer Suspension

The TORFLEX suspension system is a torsion arm type suspension which is completely self contained within the axle tube.  It attaches directly to the trailer frame using brackets which are an integral part of the axle assembly.  The TORFLEX axle provides improved suspension characteristics relative to leaf spring axles through the unique arrangement of a steel torsion bar surrounded by four natural 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, which is fastened to the rubber encased bar.  As load is applied, the bar rotates causing a rolling/compressive resistance in the rubber cords.  This action provides the same functions as conventional sprung axles with several operating advantages including independent suspension.

Inspection and Replacement

All the components of you suspension system should be visually inspected at least every 10,000 km for signs of excess wear, elongation of bolt holes, and loosening of fasteners.  Whenever loose or replaced, the fasteners in you suspension system should be torqued as detailed in the chart below.

Suspension Fastener Torque Values

Worn spring eye bushings, sagging or broken springs should be replaced using the following method.

1. Support the trailer with the wheel just off the ground.  Follow the trailer manufacturer's recommendations for lifting and supporting the unit.  Do not lift or place supports on any part of the suspension.
2. After the unit is properly supported place a suitable block under the axle tube near the end to be repaired.  This block is to support the weight of the axle only so that suspension COMPONENTS can be removed.
3. Disassemble the U-bolts, nuts and tie plates.
4. Remove the spring eye bolts and remove the spring and place on a suitable work surface.
5. If the spring eye bushings are to be replaced, drive out the old bushing using a suitable drift punch.
6. Drive the new bushing into the spring eye using a piloted drift punch of  a close fitting bolt inserted through the bushing.  Warning! Be sure to wear safety glasses when removing or installing force fitted parts.  Failure to comply may result in serious injury.
7. Reinstall repaired or replaced components in reverse order.  Note: For multiple axle units, the weight of each axle must be supported as outlined in Step 2 before disassembly of any component of the suspension system.

If the equalizer or equalizer bushings must be replaced, follow the instructions above for lifting and supporting the trailer unit and then proceed as follows:

1. With both axles blocked up, remove the spring eyebolt, shackle bolt and equalizer bolt from the equalizer to be repaired or replaced.
2. Take the equalizer to suitable work surface and remove the worn bushings using a suitable drift punch.
3. Drive the new bushings into place using piloted drift punch or a close fitting bolt through the bushing.  Caution!  Be sure to wear safety glasses when removing or installing force fitted parts.  Failure to comply mat result in serious injury.
4. Reassemble in reverse order.

All of the pivot points of your suspension system have been fitted with anti-friction bearing materials which do not require routine lubrication.  However, when otherwise servicing the unit, these pivot points may be lubricated of you so desire.

Except for periodic inspection of the fasteners used to attach the TORFLEX axle to the vehicle frame, no other suspension maintenance is required on TORFLEX axles.  They are, of course, subject to the maintenance and inspection procedures regarding brakes, hubs, bearings, seals, wheels and tires as outlined in this manual.

Warning!  Do NOT WELD on the TORFLEX Beam.  It has rubber cords inside and the heat generated by welding could damage the cord.