BPW steering axles GSLA/GSLL are designed both for self-steered and positively steered vehicles. BPW‘s steering axle GSL is a purely positive steering axle. The advantage of a GSL axle is the reduction in steering forces. In addition, this axle allows larger steering angles due to its special design.
When the trailer follows the tractor in a curve, the wheel castor ensures the wheels to turn in accordance with the curve radius.
For speeds higher than 40 km/h, BPW recommends locking the steering axle. The steering axle must be locked while driving backwards.
When cornering the tractor, the cylinder installed between the tractor and the trailer is actuated according to the curve radius. The pressurised oil regulates the movement of the steering axle.
In electronic positive steering systems, the steering axle is actuated by a potentiometer installed on the drawbar. A computer activates a hydraulic unit which again actuates the axle by hydraulic pressure.
For safety reasons, when electronic steering systems are used, BPW recommends application of steering axles type GSLL and GSLA.
Functional principle of BPW combination cylinders
Axle beam and axle stub are connected via steering pivot with wave-like thrust bearings. When driving straight-ahead (zero position), the wave-like thrust washers hold the wheels on the track. The vehicle pushes the wave contours of the upper and lower thrust washer against each other with its weight. The wheels remain in the correct and stable straight-ahead position.
When the trailer follows the tractor into a curve, the wheel castor ensures the wheels turn in accordance with the curve radius (thrust washers slide over one another). The steering axle ensures the suspension is steered better into the curve and almost follows the tractor‘s circular path. The generated lateral tyre forces are optimally distributed over all axles.
Steering housing when driving straight ahead (zero position)
Steering housing when cornering (up to 27 degrees, depending on vehicle model)