Hydraulic Press Terminology - Parts of a Hydraulic Press


A flat, stationary, machined surface that supports the lower bolster or dies.

Bed Cushion

A bed cushion is commonly required for deep draw applications and is used to apply resistance force when pushed upon. This resistance force helps to ensure the material is drawn smoothly, without wrinkling or buckling.  Bed cushion force can be dynamically controlled throughout the stroke, allowing the resistance force to change based on the position of the bed cushion.

Bed Height

The distance from the bottom of the hydraulic press structure to the working height or the top of the bed bolster. If a press requires a pit, working bed height could be defined as the distance from the floor to the top of the bed bolster.


A removable plate that serves as the working surface of a press. The plate is typically bolted to the bed and ram substructures. Tooling is attached to the bolster, which can feature a variety of work holding features such as T-slots, drilled and tapped holes, lift rails to accommodate quick die change systems, and more.

Bottom Stop

  • By Pressure: The press may be designed to ‘return on pressure’. This method uses an adjustable pressure sensing device that is set to determine the desired maximum pressure to be achieved by the ram. Once this pressure is achieved, the ram completes the cycle by returning to the ‘Home’ position or ‘Up Limit’ position.
  • By Position: The ‘return on position’ method uses a position sensing device (typically a linear transducer) that can be programmed via the Operator Interface to ensure the desired ram position has been achieved.


A fixed or removable cylindrical metal lining used to constrain, guide and reduce friction. During normal operation, the bushing provides ram guidance by traveling up and down the posts. Beckwood uses replaceable graphite-impregnated bronze bushings that do not require external lubrication.


The upper structural weldment of a press containing cylinders that drive the motion of the ram.


A complete movement of the ram, from the initial start position back to the same start position, that may include feeding and removal of the material or workpiece(s).


The main actuator of a hydraulic press.  This mechanical actuator converts hydraulic pressure into linear movement creating force


The distance between the bed bolster and the ram bolster when the ram is fully retracted. This is also commonly known as the “Open Height.”


The amount of deviation from a straight line when force is applied. This is sometimes called “yawning” in C-frame designs and expresses the amount a frame flexes under a load. Beckwood presses are designed to minimize deflection.


Hydraulic presses are capable of maintaining force for extended periods of time. This is typically accomplished by using pressure lock valves or variable volume pumps that are remotely controlled for long periods of precise pressure holding. Learn how our pneumatic dwell technology helps reduce energy consumption. <link to EE page>

Finite Element Analysis (FEA)

A computerized method for predicting how a structure will react to real-world forces (vibration, heat, fluid flow, etc). FEA works by breaking down a real object into a large number of finite elements and using mathematical equations to predict the behavior of each element. Beckwood uses FEA to engineer every press to our Infinite Life standards. (link to infinite life)


Press components that guide the reciprocating motion of the slide to ensure required squareness and parallelism. Gibs are usually provided with replaceable liners and are often adjustable to enable the setting of proper the clearance and to compensate for wear.

Heated Platens

Steel plates that have heating capabilities. They can be heated using electric rods, steam, oil, or water. These systems usually require thermal breaks (insulation) between the heated plates and the hydraulic press structure. Heating controls can be separate or fully integrated into the press control system.

Human-Machine Interface (HMI)

A touch screen interface that presents information to an operator about the state of a process or a machine. It is used to accept and implement the operator’s control instructions.

Hydraulic Power Unit (HPU)

The mechanism that applies the pressure to drive motors, cylinders, and other parts of a hydraulic system. Unlike standard pumps, these power units use multi-stage pressurization networks to move fluid, and they often incorporate temperature control devices. HPUs are typically either skid-mounted or crown-mounted.


  • Electric: An electrical machine used to turn electrical energy into rotary energy. Used in hydraulic circuits to drive hydraulic pumps.
  • Hydraulic: A hydraulic machine used to turn hydraulic energy into rotary energy. Reverse of a hydraulic pump.


A steel plate, sometimes heated, attached to a moving or stationary press member.


Abbreviation for Pounds per Square Inch, a unit for measuring pressure.



Ram (or Slide)

The moving portion of the press that slides within the press frame to create pressure on the tool or die. The ram can move vertically or horizontally depending on the application.

Ram Knockout

A device used to strip the formed part from the punch or die.

Ram Speed

How fast the ram moves from the open to closed position. Ram speed is measured in IPM (inches per minute).

  • Fast Approach Speed: Designed to lower the ram quickly during the portion of the stroke that does not require any force.
  • Pressing Speed: Commonly referred to as the ‘working portion’ of the stroke where force is required and speed is slower.
  • Stripping/Retract Force: After the Pressing portion of the stroke is completed, the ram retracts at a Fast Retract speed which affords little force.

Return on Position

Cycle is finished and ram is returned once a specified ram position is reached.

Return on Pressure

Cycle is finished and ram is returned once specified pressure is reached.

Shut Height

The distance between the bed bolster and the ram bolster when the ram is fully extended. This is commonly known as the “Closed Height.”


The total distance the ram can travel, from full extension to full retraction.

Stroke Control

The ram travel (stroke) of the press may be controlled in a variety of ways. Most hydraulic presses feature Adjustable Retract Limit Switches to restrict the retract distance of the ram (also known as the Up Limit Position). Using only the required stroke for part loading and unloading can shorten cycle times. Other programmable limits may include: Slow Down Limit for deceleration from Fast Speed to Slow Speed; Bottom Stop Position and/or Bottom Stop Pressure, etc.


A work holding feature to facilitate quick die change.

Throat Clearance

The distance from the vertical centerline of the bed to the back of the press behind the bed in a C-frame or gap frame press. This distance allows you to determine the diameter of parts and tools that can be positioned within the press.

Tie Rod

Long rods, with threads and nuts on both ends, which hold the frame members of a hydraulic press together. These rods are stretched to place the frame members under compressive load.


The maximum amount of force that can be exerted by the press. Typically called out in US tons.


  • Linear: Used to measure the position of the press ram or cylinder rod.
  • Internal Linear: A linear transducer mounted inside of a cylinder to measure the exact cylinder extension. This gives the most precise measurement of movement. Linear transducers are also offered externally.



A unit formed by welding together an assembly of pieces. A Hydraulic press has three main weldments:

  • Crown
  • Bed
  • Ram

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