TORQUE MASTER CO., LTD.

Hagglunds Hydraulic System

A complete hydraulic drive system from Hagglunds Drives comprises the Power unit with electric motor, pump and tank, the control system, the hydraulic motor and the piping system. The power unit type PEC is described in this publication and uses a closed loop hydraulic system to provide a highly dynamic drive system.

In most offerings, all items except the piping and hydraulic motor are housed in a sound insulated cabinet. The swash plate pump is driven by an electric motor running effi ciently at fi xed speed.

The oil fl ow from the pump is determined by the swash-plate angle, which is controlled by a signal from the control system. Starting in an unloaded, neutral condition, the system ramps the fl ow up to the required direction and rate
and pressure is determined by the load up to the limit set at the compensator. If pressure reaches compensator setting the pump will destroke, stopping the drive, so eliminating heat build up but maintaining the set pressure and therefore torque at the drive. The pump will stay in this condition until the system is unloaded whereupon the pump will immediately ramp up to theset fl ow rate or until the control is adjusted. The pump and the hydraulic motor are connected together by fl exible hoses and piping if necessary.

At the motor the oil is distributed through the valve plate to the pistons in the cylinder block 50% of them with high pressure and 50% with charge pressure. The oil pressure forces the piston assemblies radially outwards against the
cam-ring. This produces a balanced and smooth rotation with extremely high torque which drives the machine. The speed of the motor is controlled by the fl ow of oil from the pump. Drive motor speed is therefore proportional to the
swash plate angle of the pump. If the swash plate is controlled over-centre, the fl ow is reversed and the motor direction is therefore reversed.