Advanced Actuators & Drives

PUSH-PUMP™ Technology

Even with digital manipulation, the old "tried and true" pneumatic operator is recognized as the main obstacle to better process loop performance. The introduction of "smart" positioners increased the product price but not the necessarily the performance. The medium of operation, air, is the culprit. The compressibility of air in combination with inherent control valve friction reduces positioning sensitivity and increases response time (lag). The output stem of a pneumatic actuator is easily moved (lacks stiffness) when confronted with dynamic forces caused by pressure fluctuation in the process.

Other actuator technologies bring their own limitations to an installation. Gearmotor operators cannot continuously modulate, are high maintenance items, and do not offer a spring failsafe. Traditional hydraulic systems are expensive, high maintenance, difficult to install, and not energy efficient. Electraulic units are expensive, difficult to install, and, in general, not suited to small-to-moderate sized applications. The process control industry has recognized these impediments and is searching for the next genuine advancement in final element control.

The PUSH-PUMP™ was conceived to eliminate these barriers to improved control for routine applications. Acting as a hydraulic gearbox, the PUSH-PUMP™ converts oil flow in the pump to increased thrust or torque in the output piston. The control benefits are numerous, including high stiffness, precise positioning and energy efficiency, as shown in the chart below.

Although a powerful concept, the hydraulic circuit of the PUSH-PUMP™ is simple and effective. It is inherently lubricated; there are no metal-to-metal wear surfaces; there are no fine passages to trap contaminants; there is not a definable reservoir; the unit is insensitive to position; no heater is required and the oil volume is small.

The actuator version of the PUSH-PUMP™ is single acting; that is, pump pressure moves the cylinder in one direction. Return motion and fail-safe position are provided by a spring. Bi-directional rotation of a single motor controls motion in both directions. Once position is reached as set by the control signal and active feedback, the motor is stopped and power is not required to maintain position.

Feedback is mechanically connected to the output shaft and can be adjusted to a full stroke of less than one-half inch. Positioning accuracy is phenomenal with a repeatable resolution in the tenths of a thousandth of an inch.

A PUSH-PUMP™ -powered actuator offers more advantages and features than any other competing technology currently available in our size range.