Hydraulic cylinders

A cylinder is defined by five dimensions: the bore, which sets the force available at a given pressure, the rod diameter, which governs resistance to buckling, the stroke, the retracted pin-to-pin length, and the mounting type (clevis, spherical bearing, trunnion, cradle).

A single-acting cylinder works in one direction only, the return coming from the load or from a spring. A double-acting cylinder controls the movement both ways, at different speeds out and back, since the area on the rod side is smaller. A telescopic cylinder gives a long stroke from a short retracted length, but its force falls off stage after stage.

• Slow, unprompted drift down usually points to the piston seals; an external leak points to the rod seal or the wiper.
• A scored rod, or one whose chrome is flaking, will destroy new seals: it has to be reground or remade.
• On a suspended load, a pilot-operated check valve remains essential, whatever condition the cylinder is in.

We strip, inspect, reseal and pressure-test your cylinders, and we build new ones from a sample or from a drawing when the original part no longer exists.