Glossary

Quadratic - Another name for second order, based on the form of the equation which represents the second order response.

Quick Disconnect - A coupling usually containing at least one check valve which can be rapidly disconnected with minimal leakage.

Rabbet Mount - A mounting configuration which utilizes matching male and female forms (usually coaxial circular) between the cylinder and its mating mounting element.

Ram - A single-acting cylinder in which the movable element has approximately the same cross-sectional area as the cylinder bore. Hence, a ram has a single diameter type plunger as opposed to a piston and rod. The plunger in a ram-type cylinder is also called a ram.

Ramp Input Function - An inclined slope, a constantly increasing function, a linear intensification of magnitude.

Ratchetting - A stick-slip action (intermittent motion) of the control system.

Rated - Refers to the manufacturer's designation of the normal operating condition — the maximum, allowable, continuous, etc.

Ratio of Specific Heats - The ratio of the amount of heat required to raise a mass of material 1 degree in temperature to the amount of heat required to raise an equal mass of a reference substance 1 degree in temperature.

Reciprocation - A back-and-forth straight line motion or oscillation.

Redundancy - The existence of more than one means for accomplishing a given function.

Regeneration - The recovery of energy that would ordinarily be lost.

Regenerative Control System - A system where part or all of the output is fed back to help drive the function or is stored for driving the output converter.

Reproducibility - Quantitative expression of the random error, associated with testers working in different laboratories, each obtaining single results on identical test material, using same method. That is, the precision with which the measurement of a given quantity can be duplicated in separate facilities.

Response Time - The time required for the system output to reach and stay within a specified percentage of its theoretical final value due to a step input - usually equal to five time constants.

Restrictor - A device having a reduced fixed or variable area which creates a deliberate pressure drop and resistance to the normal flow of fluid. Variable types are noncompensated, pressure-compensated, or pressure- and temperature-compensated.

Reynolds Number - The dimensionless ratio of dynamic force due to mass flow to the shear stress due to viscosity.

Remote Power Skid - Some press applications may require that the hydraulics be located remotely from the press itself. Other applications may preclude the power system from being able to be installed at the top around the crown structure of the press. In these cases, the power system and even the controls may be designed into a separate unit capable of being placed adjacent to the press or away from the press.