US Patent 7637407 Fastener gun

An example fastener gun includes a housing having a plunger and a power spring for driving a fastener into a workpiece, and a trigger arm pivotally attached to the housing at a trigger pivot. The trigger arm lifts the plunger to bias the power spring when the trigger arm pivots in a first direction. The example fastener gun also includes a handle extending upwardly from the housing and pivotally attached to the housing at a handle pivot, and a roller for pivoting trigger arm in the first direction when the handle moves toward the housing. The roller moves away from the trigger pivot when the handle moves toward the housing.