Turntables can be a cause of steering problems.
You may not be aware of the influence a turntable can have over the Steering performance of a truck / trailer combination. Problems with turntables can result in vehicle wander, darting and make small steering corrections difficult causing driver fatigue.
There are two types of turntables, greased plate and ball race. In both cases the connection between the truck and trailer must be in good condition, free to pivot for best steering performance.
Because turntables are under up to 12 Tonnes of force this makes there condition critical when changing lanes or completing fine maneuvering such as reversing a trailer into a dock or down a narrow road.
When a vehicle changes lanes or overtakes, the driver applies right hand lock and the prime mover begins to turn, the trailer tries to pivot around the turntable. If there is too much friction the trailer begins to push the prime mover, force builds up at the turntable and suddenly the resistance (friction) reduces. This will cause the vehicle to oversteer or over react darting across the road. To bring the vehicle back onto the correct course requires continuous adjustment by the driver, as this process repeats.
Ball Race Turntables
Ball Race turntables are not immune. They are often poorly sealed and road grit can contaminate the ball tracks resulting in a huge increase in resistance (friction). To check your Ball Race turntable spin the turntable balls, if you hear a heavy rumble noise then there is likely contamination in the balls and high resistance to turning.
Greased Plate Turntables
Greased plate turntables must be regularly cleaned and re-greased. Look for signs of galling or gouging if these are apparent the service intervals are too long. Galling occurs when friction causes the metal surfaces to tear each other, A galled turntable is a definite sign that the vehicle has had its steering performance seriously impaired. Consider fitting one of the low friction overlays to the turntable , these reduce maintenance and significantly cut friction.
For more information contact Hydrosteer www.hydrosteer.com.au