Spring-return pneumatic valve actuator
685 500 lb.in. | biffi Tyco Valves & Controls

Scotch yoke design generates high break torque needed for the actuation of many quarter-turn valves.
Six bearings provide reliability, smooth operation and extended service life:

Two bronze yoke bearings ensure minimal friction.
Two bronze sliding block bearings spread load over large surface area.
Guide block bearing and piston rod bearing of sintered bronze impregnated with PTFE increase efficiency, reduce maintenance and prolong actuator life.

Graphite-impregnated PTFE piston bearing reduces friction between the piston and cylinder bore and allows the cylinder to be operated without lubrication.
Guide bar supports the transverse forces and insures proper support of the piston rod.
Hard chrome plating on guide bar provides corrosion resistance and minimal friction loads.