MIT COLLEGE OF ENGINEERING, PUNEDEPARTMENT OF MECHANICAL ENGINEERING

HYDRAULICS & PNEUMATICSLAB MANUAL

Name of the experiment: Testing of Linear actuator

Aim: To test a double acting cylinder to decide safe working range

Theory of Actuator:

A double acting cylinder is examle of linear actuator. This is widely used for lifting of loads, pulling of loads, machine tool operations etc hence its safe working range must be known.

A typical cylinder is shown. (Refer figure number 1 )

Pressurized oil from pump will enter full bore end, pushing piston. This is extension stroke. Speed of extension wiil very as per supply pressure. so also it's load handling capacity.

Maximum pressure any cylinder can handle is related to oil seal capacity also.Oil seal location is shown in figure number 1.

During return stroke, oil enters port "B" thus oil in full bore end will be driven out through port "A". Return speed, theoretically is more than forward stroke because of area difference. Time for extension + time for return is called as cycle time.

At different pressures, speeds & load capacities are different which must beknown for design purpuse.

In this experiment these parameters are tested.

Precautions:

Pump used for testing is positive displacement pump. Therefore no blockages in circuit are permitted.

Before starting set system pressure must be at minimum value.

QC couplings must be properly secured.

Check default position of DC valve first.

Set system pressure to minimum before switching off the pump.

Appratus: Hydraulic trainer, stop watch, stop watch

Observations:

Piston dia: Rod dia: Stroke length:

S.No

system actual time return Pressure Pressure ext. return pressure

sec sec

Calculations:

Piston area: Annulus area:

Safe stress for bending:

Extension stroke

S.No.

Actual extension th. Load Bending pressure speed lifting stress

capacity calcultedbar m/min KN

Return stroke

S.No.

Actual Return th. Load pressure speed pulling

capacitybar m/min KN

P1

P2

P3

P2

P3

Sample calculations: (Write excel formula)

Piston area:

Annulus area:

Extension speed:

Return speed:

Load lifting capacity:

Load pulling capacity:

Bending stress:

Graphs: Actual pressure vs extension speedActual pressure vs return speedActual pressure/load vs bending stress

Concluding remarks:

MIT COLLEGE OF ENGINEERING, PUNEDEPARTMENT OF MECHANICAL ENGINEERING

HYDRAULICS & PNEUMATICSLAB MANUAL