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.
There are two types of turntable , greased plate or ball race. This connection between the truck and trailer must be in good condition and free to pivot if steering performance is not to be jeopardised.
Think about what happens when you start to over take a vehicle on the road, the driver applies a slight amount of right hand lock and the truck begins to turn and the trailer pivots about the turntable. If there is excessive friction at the turntable as the truck begins the turn , a resistance to turn is applied by the turntable until enough force at the turntable to overcome the friction. Once this happens the resistance breaks and the vehicle will oversteer or over react darting across the road. To bring the vehicle back on line the same happens resulting with the driver sawing away at the steering wheel whilst trying to maintain their course.
There may be 12 tonnes of load on the turntable and obviously it must be in good condition to turn freely under load.
Never assume that because you have a ball race turntable inspection or maintenance isn’t required. Ball race turntables are often poorly sealed and road grit can get in and contaminate the ball tracks resulting in a huge increase in friction. Spin the turntable and if you hear a heavy rumble noise then imagine how it would be under load.
Grease plate turntables must be regularly cleaned and regreased. Look for signs of galling or gouging if these are apparent the service intervals are too long.Galling occurs when , because of friction, the metal surface tears at the interface of the two surfaces. 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 over a poorly maintained turntable.
For more information contact Hydrosteer http://www.hydrosteer.com.au
Hydrosteer 