These lifts have a 3 tonne lifting capacity and conform to BS AU161 part 1a 1983.
The electric motor, hydraulic pump and oil reservoir form a power pack which is mounted on the control column.
Raising the operating handle will start the electric motor and cause the pump to diliver oil via a non-return valve to the ram beneath the power track.
The hydraulic pressure in the ram will retract the piston, at the same time pulling on the rope system and raising the platform
If the platform is raised to the extent of its travel, it meets a mechanical stop. This causes an increase in the hydraulic system pressure which forces the control handle to the neutral position and stops the motor.Pressing the operating handle down will by-pass the non-return valve and allow the oil to return to the reservoir as the lift decends. Up to a predetermined maximum, the rate of decent is dependent upon the vehicle weight.
The raise/lower control is of the "deadman" type and will stop the lift if released.
A pressure relief valve in the hydraulic system limits the maximum hydraulic pressure obtainable. Should the lift be overloaded, the relief valve will open allowing the pump output to be returned to the oil reservoir, while the lift remains stationary
A variable restrictor is fitted in the hydraulic cylinder inlet/outlet connection. In the unlikely event of a failure of the hydraulic line or connections, the resultant rush of oil forces the restrictor on to its seat, thus reducing lift descent to a safe speed
A clutch rod is suspended from the top of each column. A spring loaded ring clutch rises and descends with the lift. Should a cable fail or slacken then the clutch ring tilts and grips the rod. This provides an emergency support for the lift at that column.