WORKING PRINCIPLE OF DOUBLE ACTING HYDRAULIC CYLINDER

We were discussing hydraulic actuators and its various types in our previous post, where we have seen the basics of hydraulic actuators and simultaneously we have classified the hydraulic actuators in linear actuators i.e. hydraulic cylinders and rotary actuators i.e. hydraulic motor. We have also seen the fundamentals of single acting cylinders in our previous post.

Today we will see here the fundamentals of double acting hydraulic cylinders

Double acting hydraulic cylinders

Double acting hydraulic cylinder is also one type of hydraulic cylinder which is used for pulling, lifting, moving and holding the load. Double acting hydraulic cylinder is displayed here in following figure. Double acting hydraulic cylinder, as shown in figure, will have two ports i.e. cap end port and rod end port. Double acting hydraulic cylinder, as name indicates, will be operated hydraulically in both direction i.e. forward direction and return direction.

Double acting hydraulic cylinder will have one piston within a cylindrical housing. When hydraulic oil will be supplied to its cap end port, hydraulic pressure force will be applied over the piston or plunger and hence piston will be extended and this stroke of cylinder will be termed as forward stroke. During extension of the cylinder piston or plunger, hydraulic oil at rod end side will be pushed out and will be directed towards reservoir.

Double acting hydraulic cylinder

For return stroke or retraction of cylinder, hydraulic fluid direction will be reversed with the help of direction control valve. During return stroke, hydraulic oil will be supplied to its rod end port and therefore hydraulic pressure force will be applied over the piston or plunger from rod end side and hence piston will be retracted and this stroke of cylinder will be termed as return stroke. During retraction of the cylinder piston or plunger, hydraulic oil at cap end side will be pushed out and will be directed towards reservoir.

Working of double acting hydraulic cylinder

Hence double acting hydraulic cylinders will be operated hydraulically in both directions i.e. during extension or forward direction and also during retraction or return stroke. Direction of hydraulic oil will be changed with the help of double acting directional control valve or reversible pump could also be used for changing the direction of flow of fluid.