Pressure is expressed as force per unit area. In the SI system units of pressure are Pascals (N/m2) or Bar (=10 mPa). In Imperial Units, pound per square inch (psi) or lb/ft2.

Actuator force ratings are commonly based on 3,000 psi (207 bar = 20.7 mPa).
You can approximate the actuator area by dividing the force rating of the actuator by the pressure.

A = F/P

Imperial Units
A = square inches
F = lbf
P = lbf/square inches

SI Units
A = square cm
F = kN
P = .1kN/cm2 = 1 mPa

For dynamic applications some of the total system pressure needs to be available to move oil through the valve. Typically, for those applications force calculations (F = PA) are based on 2,000 psi (138 bar = 13.8 mPa)

Actuator Accessories
Swivel Bases and Swivel Rod Ends are actuator accessories which have a semi-spherical bearing with an adjustable preload mechanism. They reduces backlash in a test setup while maintaining the freedom to pivot.  Proper preload reduces friction, minimizes impact noise, and during load reversals encountered in high-frequency testing improves the waveform.

An actuator equipped with both a swivel base and a swivel rod end has the freedom to pivot at both ends. That minimizes moment loads on the piston rod bearings and load cell.

Spiral washers are easy to use devices, Spiral Washers preload elements of the load train to provide backlash-free connections. When placed over threaded studs, each half is rotated in opposite directions, placing a steady state preload on the stud. Typically they are used for attaching swivels and force transducers to an actuator..

91 Series Actuators

Shore Western’s 91 Series actuators are our most popular with their proven design and performance they are the choice of thousands of engineers worldwide. These fatigue rated linear actuators come standard with either 6 inch (150 mm) or 10 inch (250 mm) stroke lengths and force ratings from 1.1 KIP (5 kN) to 330 KIP (1500 kN). Typical applications include

  • Structural fatigue testing
  • Fatigue testing of structures and components
  • Vehicle durability testing

91 Series Actuators set the standard for actuator design unmatched in extreme and grueling test conditions. Advanced design, quality components, and variety of options makes the 91 Series Actuator your best choice for testing applications.

 

Features

  • Bonded polymer bearings — Shore Western utilizes non metallic bearing surfaces for all bearings to provide long life and resist bearing-to-rod galling failures. Bonded polymer bearings offer high side-load and high velocity.

  • Sideload tolerance — If the forces acting on an actuator piston rod are not aligned with the direction of piston rod motion side loading occurs. Side loading mars test results and reduces the actuator life. Large bearings and the application of proprietary materials give the 91 Series Actuators high side load capabilities.

  • Displacement transducer — All actuators have a coaxially mounted LVDT in the piston rod. Actuators can be configured with either an open housing or a closed housing for attaching a swivel or pedestal base. Typical component or structural test applications call for a closed housing and swivel base and rod end.

  • Hydraulic cushions — The piston and end caps are protected during full stroke or high-velocity operations by hydraulic cushions.

  • Large diameter piston rod — 91 Series Actuators use hollow, large diameter, one piece piston rods made of 100,000 psi yield material for infinite fatigue life, providing strength and maximum lateral stiffness. The chrome plated piston rod is micro ground and super-polished to minimize friction in severe service and extend seal and bearing life.

  • High pressure seals — 91 Series actuators come standard with high-pressure seals designed for low friction, long life, and outstanding performance in high-frequency/low-displacement applications. For applications where reduced frictions is a requirement an actuator can be supplied for operation without high pressure seals.

  • Piston rod wiper/seal — A low-pressure wiper/seal provides for both a hydraulic seal and a rod scraper to help eliminate external contamination of the bearings and internal seals.

Options

  • Flow options — Servo valve manifolds with oversize ports and provisions for interfacing to a variety of servo valves and service manifolds are available. Their design provides for fluid conditioning and low/high pressure control and allows the actuator to accept a number of servo-valves. Optional dual servo valve and three-stage servo valve configurations are available.

  • Swivels and base ends — The 99 Series Base Ends and 98 Series Rod End Swivels or Shore Western’s Ball Swivels can help reduce side loads and force alignment problems and eliminate backlash in test setups.

  • Load washers — Load washers preload force train element connections to avoid backlash and fatigue failure between attached components. Available in varying thickness load washers let you quickly preload attached components.

  • Stroke lengths — Custom stroke lengths are available upon request, adapting the 91 Series Actuators to test requirements not served by the standard strokes of 6 and10 inches (100 and 250 mm).Custom stroke length actuators may also require a custom LVDT.

  • Load cells — Load cells and differential pressure sensors are avaliable for every force rating.

  • Trunnion and gimbal fixtures — Are available for testing applications requiring a controlled or restricted range of motion.