A very low first ratio in a truck transmission, tractor or bicycle, often around 6:1 to 7:1 in four-speed truck gearboxes, meant for starting a heavy load, crawling or climbing steep grades. Drivers usually start in second and save the granny gear for when it is needed. The word marks the gear as slow and powerful rather than weak.
Heard on the job
Loaded with gravel on that grade, put it in granny gear and just let it walk up the hill.
Also heard as
- granny low
- creeper gear
Related terms
Gear ratio
The number of teeth on the driven gear divided by those on the driver, setting speed reduction and torque gain.
Crash box
Shop name for an unsynchronized manual gearbox, where shifts grind unless engine and road speed are matched.
Box
Shop shorthand for a gearbox, reducer or transmission, as in the box is whining or pull the box.