A rack clamp consists of a frame, two jaws, a screw, a handle and a spring.
Frame
The frame is also known as a bar, and it is the largest part of the clamp.
Usually, one end curves round to make up the fixed jaw, whilst the moveable jaw rests on the other end of the frame, and can be manoeuvred along it.
The length of the frame determines how wide the jaws of a rack clamp can open.
Jaws
The purpose of the jaws is to grip on to the workpiece during clamping.
A rack clamp has two jaws, which are parallel to one another.
One jaw is fixed and cannot be moved. The other jaw is moveable and can be adjusted, allowing the jaws to be opened and closed.
The moveable jaw is spring-loaded, meaning when pressure is placed upon the spring, the jaw is loosened and can be re-positioned. It can also be disconnected from the frame and reversed, for versatility.
The moveable jaw commonly has a groove in its surface, to allow the clamp to grip on to tubed or irregularly shaped objects.
Spring
A rack clamp has a spring which allows the moveable jaw to be adjusted when pressure is placed upon it. Similarly, when the pressure is removed the spring ensures the jaw stays firmly in position.
Screw
A rack clamp has a small integral screw which controls the moveable jaw by placing pressure on the spring when rotated. The end of the screw is fitted with a collet for the handle to pass through.
Handle
The handle is used to rotate the integral screw and adjust the moveable jaw. A rack clamp usually has a long, thin sliding pin handle, which makes it easy to gain extra leverage when tightening the screw.
When the handle is turned anti-clockwise jaw will open and when it’s turned clockwise the jaw will close.