the reply from bley is correct the unit will not stop as a conventional forklift the park brake is either applied from the the dashboardor the inching pedal when fully depressed after two seconds the park brake will engage as he pointed out the test to do on the inching pedal disconnect switch under inching pedal fully depress it and put unit in drive full revs if unit moves adjust the inching valve at the lever so unlock the lever the shaft has a screwdriver slot turn shaft anticlockwise to shut of drive when pedal is fully depressed one other test that you should do is pick up heavy load place unit on an incline and engage park brake the unit should hold no movement if truck moves you need to investigate brake valve which is at the front of unit on its own just above the 6 port valve if valve appears ok you could have front wheel motors leaking internally which is usually diagnosed when removing outer plate of wheel motor if oil is present motor has to be changed but if all units are the same i would also say the operator does not understand the units operation