Maintenance of farm vehicle suspension
About 35 years ago, most farm trailers, were only about 3 to 5 ton capacity and single axle. A single axle needs no suspension thus trailers required very little maintenance. Around that time I believe I remember there was an explosion of bigger trailers of 8 and 10 ton with 2 axles. Two axles require suspension and most farm trailers use shackle pins or rocking beams with bushes requiring frequent greasing. We have recently noticed an upsurge in suspension repairs both with our own and customers trailers. In order to combat these failures we have increased our greasing frequency. As well as this increased frequency we also, regularly, grease the suspension while the trailer is jacked up and supported under the chassis. This allows the pins to drop to the other side of the bushes thus allowing the grease to occupy the vacated space (the load bearing side of the pin / bush).
Another recurring failure we have encountered recently is with certain models of 4WD tractors. Many manufacturers are now using muff couplings on the front prop shaft instead of universal joints. The problem being, that if the trunion bushes become worn, the front axle becomes miss aligned, and the muff couplings can't accommodate the misalignment and so the splines will fail. This is an expensive repair because the spline which protrudes from the rear of the front diff is part of the pinion which is matched with the crown wheel and thus only available as a pair. Although our tractors and telehandlers all use UJs in the prop shafts, so avoiding the spline failures, we still don't want the trunions to fail so we are taking extra care with the greasing, including jacking up as described above. This is now our standard practice with all our own and our customers equipment. It is usually possible to build up these trunnions, please ring for advice and ask for John Parlour. 01609 773607
Occasionally, if there is already considerable wear, the above method of greasing may not work, so I made this thin pipe for squirting grease into small gaps between bush and trunion, see pic, it works well and is easy to make from a piece of bundy tube (automotive fuel etc. pipe) available from auto factors or us. Just thread one end and screw in a grease nipple and flatten the other end with a hammer you can get it really thin without blocking it but be careful. You can also file it to make it even thinner.
We have done a little research into the best grease for this purpose and have chosen to use molly grease. We now regularly use Molybdenum Disulfide grease on ours and customers equipment where sliding occurs eg. pins bushes, the sliding mast on telehandlers, splines etc. Click here for more info on Molybdenum Disulfide.