If the front wheels lock the vehicle skids in the direction it is currently travelling and it can no longer be steered. The causes: possibly the wrong brake linings fitted at the rear of the vehicle, a wrongly-adjusted or faulty brake proportioning valve, oily or worn-out rear brake linings, worn-out or damaged rear brake discs or drums, a defective rear wheel brake circuit. Immediately take your vehicle to a specialist workshop or ATE BrakeCenter to find the cause of the problem. And use Original ATE brake parts to repair the fault.