GENERAL INDUSTRIAL / SPECIALTY
Self-Locking Cylinders (HYS/PVS)
LOCK-ON-RETRACT
Click on image to see it in motion
Lock on retract (LOR) Cylinder Types
PVS (Pneumatic/Air/Light Hydraulic)
PVS Style Self-Locking Cylinders are commonly used for applications using air. Often the PVS model replaces or substitutes for more costly hydraulic systems. The solid metal-on-metal lock allows for high loading without the "squish" associated with standard air cylinders.
HYS (Heavy Hydraulic)
HYS Style Self-Locking Cylinders are commonly used for applications where high moving forces are required. HYS is the perfect choice in applications where holding during loss of pressure is critical.
Accommodation of Locking Clearance / Overtravel
Self-Locking Cylinders must fully retract to lock at the end of stroke. In many applications, the lock point is not restricted and the cylinder fully extends and locks. In other applications, a more precise lockup window is desirable and may be obtained with simple stops and shims.
To ensure locking, the cylinders are manufactured with .004" to .013" of overtravel (end play) beyond the seating lock position. When pressure is removed or load applied after a locked condition is achieved, the rod will backup or move until the clearance is taken up. The overtravel clearance may be eliminated by adjusting load position at the rod-to-load interface. Consult a PFA Applications Specialist for details.
How it works
As the cylinder reaches end-of-stroke, the rod engages a keeper slide allowing the tri-sectional ring (D), to be forced into the annular groove (E) by the locking slide (F). The locking slide is held in place by the bias springs and will maintain lock-up until pressure is applied to the extend port. The extend port supplies pressure to move the locking slide off the three locking segments and to extend the rod at the same time.