TORONTO, Ont. – Jules Guillemette, product development manager, steering axles, IMT Corporation, and a speaker at this year’s Canadian Fleet Maintenance Seminar, advocates a 15-step procedure for the maintenance of self-steer axles. Here’s his advice:

1. In starting maintenance first ensure everything is in good working order. The suspension should be the right model and capacity. Install a suspension shock kit if unusual axle hop or bounce is experienced.

2.Check for mechanical looseness/wear/damage on the suspension/axle/frame and all other components.

3. Verify toe-in.

“The method is to paint a broad band on the tires on both sides, and scratch a fine line, exactly perpendicular to your spindle and your bearing, which can be used for measurement and that is done to eliminate all variations in tire tread and wheels that are not actually true. Measure front and back, and the front must be 1/16 narrower for toe-in. In doing that you’ll have proper toe-in,” said Guillemette, to delegates.

4.Verify alignment. “This is very specific,” said Guillemette. “‘Y’ is the distance of the axle kingpin to the trailer kingpin. If Y1 is not = to Y2, the kingpins can be at two different positions, and then the rest of the alignment will show properly but the wheels still won’t be pointing forward.”

This would result in tire wear, since the centralizer will fight the tendency for the tires to straighten when the axle is going forward, said Guillemette.

5. Verify the caster. “The caster is set at the time that the axle is welded into the suspension at the factory. Check this during maintenance because several factors can affect it. If you’re switching tractors fifth wheel height could vary and change the position of the caster setting,” he said.

6.Diametre of the tires are fairly important. Keep as designed and as specified. Tires must be:

(a) Same size designation and tread.

(b) Same type: all radial or all bias ply.

(c) Balanced.

(d) Inflated to recommended pressure for actual load.

7. Rims (both sides) must be the same part number and mounted the same way. “There are some rims that are very close in the offset,” said Guillemette.

8.Hubs and drums (both sides) should be the same part number with balanced drums preferred.

9.The brakes (both sides) must be the same size and adjusted the same way.

“It’s very important to have the same friction, especially for self-steers,” said Guillemette. “If you don’t have exactly the same lining on both sides, one side will brake more than the other, and every time you brake your self-steer will want to turn. The original length push rods should be used. Your brake package must be completely self-contained on the wheel. Always contact the manufacturer if you have any doubts,” he said.

10. Wheel bearings should be adjusted correctly.

11. Check for wear in the kingpin and bushings.

12. The steering damper and/or torpress should be installed and in working condition.

“It should be adjusted to give good solid resistance to shimmy and stabilization but still allow full turning of the axle,” said Guillemette.

“A manual operation involves putting a regulator in-line and sending the pressure for the centralizer. A load-sensing valve works very well, taking the pilot from the primary suspensions. The pilot will set the valve and adjust the pressure in the centralizer. If there is more load on the primary suspensions, then there will be more pressure and more centralization.”

13. The reverse lock should be installed and working.

It takes a signal from one of the suspensions and it’s a device almost identical to an ABS sensor, noted Guillemette. As soon as reverse direction is detected the suspension is lifted, he said.

14. A good check for adequate clearance between frame, tie-rod, air chamber and tires at maximum turning angle is always required, said Guillemette.

15. Lastly, verify that the axle is installed with the thrust washer below the beam.

The kingpin itself is held in place in most self-steers today by draw keys. These should be torqued to 50 ft-lbs, said Guillemette.