Mumbai University > Electronics and telecommunication > Sem 7 > Applied Hydraulics

Marks: 08

Years: MAY 2016

The hydraulic lifts are of two types normally

1. Direct acting hydraulic lift

2. Suspended hydraulic lift

3. Direct acting hydraulic lift :- It consists of a ram, sliding in fixed cylinder as shown in fig, At the top of the sliding ram, a cage(on which the persons may stand or goods may be placed ) is fitted. The liquid under pressure flows into the fixed cylinder. This liquid exerts force on the sliding ram, which moves vertically up and thus raises the cage to the required height.

The cage is moved in the downward direction, by removing the liquid from the fixed cylinder.

1. Suspended Hydraulic lift :- Fig shows the suspended hydraulic lift. It is a modified form of the direct acting hydraulic lift. It consists of a cage(on which person may stand or goods may be placed) which is suspended from a wire rope. A jigger, consisting of a fixed cylinder, a sliding ram and a set of two pulley blocks, is provided at the foot of the hole of the cage. One of the pulley block is movable and the other is fixed one. The end of the sliding ram is connected to the movable pulley block.

A wire rope, one end of which is fixed at A and the other end is taken round all the pulleys of the movable and fixed blocks and finally over the guide pulleys as shown in fig, The cage is suspended from the other end of the rope. The raising or lowering of the cage of the lift is done by the jigger as explained below.

When water under high pressure is admitted into the fixed cylinder of the jigger, the sliding ram is forced to move towards the left. As one end of the sliding ram is connected to the movable pulley block and hence the movable pulley block moves towards the left, thus increasing to the distance between two pulley blocks. The wire rope connected to the cage is pulled and the cage is lifted. For lowering the cage, water from the fixed cylinder is taken out. The sliding ram moves towards right and hence movable pulley blocks also moves towards right. This decreases the distance between two pulley blocks and the cage is lowered due to increased length of rope.