External stroke adjustors permit 0-30° of adjustment at the end of rotation. The adjustor stop, which contains the port, is set in position with a wrench on external flats and locked in place with a jam nut against a thread seal.
Cushions are designed to provide smooth deceleration, external energy absorption and noise reduction, over the last 15° of rotation.
Cushions trap fluid at the end of stroke by locking or restricting the discharge port. The trapped fluid is diverted through a small needle valve which generates a back pressure on the discharge side of the piston.
This back pressure resists the forces exerted on the internal parts of the rotary actuator, thus causing a slowing of the external mass.
Internal stroke adjustors permit 0-5° of adjustment. A threaded bushing within the end cap is set in position by a hex wrench inserted through the port and locked in place with a set screw.
* See Caution note here.
The 0-5° internal stroke adjustor and the adjustable cushion are combined into a single option. This design permits the full cushioning effect at any stroke adjustment setting.
External stroke adjustors (0-30°) and adjustable cushions are not available on single rack hydraulic units. Double rack units can be specified with external stroke adjustors on one rack (or ends) and adjustable cushions on the other rack (or ends).
When independent adjustable cushions and external stroke adjusters are used, the cushioning effect will be reduced by the amount of stroke reduction.
* See Caution note here.
Caution: Cushion needles should be set between one half and one full turn from seated position. Setting should result in continuous speed reduction throughout the cushion length. Needle adjustment is set too tight when there is an abrupt change in speed as the actuator enters the cushion. Never operate with needle in seated position or unscrewed beyond the point where the seal relief in the thread is visible
Caution: Cushion needle adjustment is a crucial factor in achieving optimum cushion performance. If the needle valve setting is too far open, cushion capacity will be reduce, or rendered ineffective; if set too tight, cushion action will generate shock and pressure spikes in excess of actuator rating.
Note: Cushions and external stroke adjustors are not available on the same cylinder end cap for standard models. Consult factory for special design considerations.
