Johnson bar (vehicle)

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
A Johnson bar for a parking/emergency brake in a 1930s White transit bus.

A Johnson bar is a hand lever with several distinct positions and a positive latch to hold the lever in the selected position. The latch is typically activated with a spring-loaded squeeze handle on the lever so that only one hand is needed to release the latch, move the lever, then re-engage the latch in a different position; this is an American English term; in British English, the lever is named for its function.

Many steam locomotives have valve gear controls which are set using a Johnson bar as referenced in Fred Eaglesmith's Back There: Hey Porter, tell that engineer, tell him this train's too slow. Tell him to let go that Johnson bar. I got places I got to go.

Many trucks and buses use a hand brake which is controlled with a Johnson bar; these are sometimes called "Johnson bar brakes".

Truck drivers call the lever control for air-operated trailer brakes "Johnson bars".

On Caterpillar tractors, the forward/reverse lever is also called a Johnson bar.

Some light general aviation aircraft (including Piper Cherokees, Beech Musketeers, and some early model Cessnas – such as the Cessna 140) use Johnson bars to actuate flaps and wheel brakes; the Cessna 162 Skycatcher uses a Johnson bar for flap operation. A small number of older aircraft (including the Mooney M-18 and some older M20s) also have landing gear actuated by Johnson bars.

On the Boeing 707/720 aircraft, the Johnson bar was used to manually extend the nose landing gear; this was only used if the normal gear extension failed.[citation needed]

See also[edit]