Piston Rod

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piston rod

[′pis·tən ‚räd]
(mechanical engineering)
The rod which is connected to the piston, and moves or is moved by the piston.

Piston Rod


a round rod that connects a piston to a slide block in reciprocating machinery—for example, pumps, compressors, steam engines, and some internal-combustion engines—or in the hydraulic or pneumatic mechanism of a reciprocating drive. A piston rod is used when the compartments formed on both sides of a piston are employed. When only one of the compartments formed in a cylinder of a reciprocating machine is used, a piston rod is usually not provided and a connecting rod is connected directly to the piston.

A unilateral piston rod is located on one side of a piston and passes through one head cover. A bilateral piston rod passes through two head covers; such a piston rod is used to provide better alignment of a heavy piston in steam-driven machinery or to connect a second cylinder in a compressor.

In some reciprocating hydraulic drives, a cylinder is attached to the moving part, or table, of a machine and a piston rod is attached to the bed. Hydraulic fluid is supplied through the piston rod to the compartment formed in the cylinder.

The diameter of a piston rod is usually determined by the rod’s strength, stiffness, and stability. However, in reciprocating hydraulic drives, it is sometimes determined by the required velocity ratio of the to-and-fro motion at a constant pump capacity.


References in periodicals archive ?
Rainer Strutzberg, head of work planning, points out a peculiarity of piston rod production.
Gasses tapped off the barrel flow down the plug through one of two metering orifices, and cause the cylinder and piston rod to move rearwards.
Unfortunately, when the rod eye was cut off from the old piston rod, it was clear that the old piston rod had rusted so much it had formed into one piece with the rod eye.
If hydraulic fluid, dirt, grease and grime accumulate on the piston rod and scraper ring, they could gum up the works and stick the lock in the down position (engaged) when all power is removed from the aircraft.
Other features include a positioning feedback mechanism included with the cylinder, which links the controller to the piston rod.
Their tiebars do double duty as hydraulic pistons to pull the mold shut as oil flows from one chamber inside the piston to another chamber via a valve inside the piston rod.
The cylinder is inverted, so the chrome piston rod remains protected from debris and damage at all times.
Key statement: The shock absorber includes a flee floating pressure tube that is able to expand or contract axially without breaking a seal, a hybrid piston rod with a shaft of one material that compensates for differing thermal expansions and a cap of another material that absorbs axial forces, a unique rod guide assembly with a biasing member that compensates for differing thermal expansion, and a unique cylinder end assembly with a biasing member made from springs, a rubber block or pressurized gas.
Injected with Teflon, the one-piece cylinder has a steel piston rod that is through-hardened and hand diamond lapped to a 2 micron finish.
The basic version has a stainless steel piston rod, magnetic piston and fixed cushioning but there are many options available.
To change from one to the other, the two-platen machine transfers oil from one chamber to another via a valve in the piston rod [ILLUSTRATION FOR FIGURE 1 OMITTED].
Excessive wear on the shoulder pins and piston rod on the recoil mechanism can also cause vibration.