Hydraulic cylinders are built in three common constructions. The choice affects pressure rating, repairability and the envelope the cylinder needs on the machine.
Welded body
The tube is welded to the end caps, which gives the most compact and lightest cylinder for a given bore. Welded cylinders are the default for mobile machinery where space and weight matter, and where the cylinder is replaced rather than repaired in the field.
Tie-rod
End caps are held by four tie rods, so the cylinder can be opened and resealed without cutting. Tie-rod construction suits industrial installations with long service life and planned maintenance windows, and it tolerates higher continuous pressure with a larger rod envelope.
Mill type
Mill-type cylinders use thick-walled tube and bolted or flanged end caps for heavy continuous duty — steel mills, presses and marine applications. They are the heaviest option and are specified when shock loads and long duty cycles dominate.
How to choose
- Mobile machinery, weight sensitive: welded
- Industrial, repairable in place: tie-rod
- Heavy continuous duty, high shock: mill type
Pressure rating, mounting and rod options are available in all three constructions, so the body type should be decided together with the duty cycle rather than after the bore is fixed.