Abstract: A driver return assembly for an electro-mechanical fastener driving tool. The tool is of the type provided with a driver which is frictionally moved through a working stroke by means of an electrically driven flywheel which presses the driver against a support element, such as a counter rotating flywheel, a low inertia roller, or the like. The driver return assembly comprises at least one elastomeric cord being attached at one of its ends to the driver and at the other of its ends to an anchor within the tool. The at least one elastomeric cord, between its ends, passes about at least two pulleys. One of the pulleys is mounted on a spring supported shaft to compensate for stretch of the at least one elastomeric cord to assure that the driver is returned to its normal, retracted position after each working stroke.

Abstract: A control arrangement for an electro-mechanical tool is disclosed. The tool may, for example, be a nailer or stapler, and is provided with an impact member which is frictionally moved in a working stroke by means of an electrically driven flywheel, which presses the impact member against the support element, which may be a counter-rotating flywheel. A solenoid is provided to move the impact member into the bite between the flywheel and support element. A trigger actuated switch and a safety switch actuated by contact of the tool with the workpiece must both be actuated in order to energize the solenoid. Circuitry is disclosed which makes possible the energization of the solenoid by closing both switches in any order, or in a desired particular order, and makes possible the provision of a time delay safety.

Abstract: An impact member for driven flywheel impact devices, such as nailers and staplers, is disclosed which may be configured to tailor the normal force as a function of ram position. A basic configuration is a constant taper, which, as soon as the impact member is actuated by a flywheel, assists in maintaining driving friction on the impact member. The taper may be linear, stepped or curved, and symmetric or asymmetric about the longitudinal axis of the ram, whereby to tailor the impact member speed for different purposes.