Grease Gun
A workshop tool used to apply grease under pressure to grease fittings (zerks) on steering and suspension joints.
A grease gun is a hand-operated, pneumatic, or battery-powered tool used to apply grease lubricant under pressure to grease fittings (zerks) on mechanical joints. It consists of a barrel that holds a cartridge of grease, a plunger assembly, a pump lever, and a flexible hose or rigid pipe tipped with a grease coupler that snaps onto the zerk fitting.
In automotive repair, grease guns are used to lubricate chassis parts that contain moving joints, such as ball joints, tie rod ends, sway bar links, control arm bushings, and universal joints (U-joints). Forcing fresh grease into the joint displaces old, contaminated grease, road grit, and moisture, reducing wear and preventing rust inside the joint.
When greasing a joint, the zerk fitting should be wiped clean first to avoid pumping dirt into the bearing. The grease gun is pumped until the rubber boot on the joint begins to swell slightly. Over-filling can rupture the rubber boot, exposing the joint to road grime and leading to premature wear. Some modern sealed chassis parts do not have grease fittings, but greaseable aftermarket parts remain popular for durability.