Abstract: An improved, large capacity, self-propelled, walk-behind power tool, such as a lawn mower, employs a parking brake apparatus which is operative to effectively brake the drive wheels of the tool. The described apparatus is activated by a foot pedal and employs locking fingers having a cooperating lost motion coupling which relieves having to maintain close tolerances for the apparatus during manufacture.

Abstract: A safety cut-off system prevents the running of a motor of a self-propelled lawn mower having left and right drive wheels, and forward and reverse gears. The safety cut-off system includes a first forward presence lever manipulatable, by an operator, between an ON state and an OFF state, wherein the forward presence lever is biased to the OFF state, and a reverse presence lever manipulatable, by an operator, between an ON state and an OFF state, wherein the reverse presence lever is also biased to the OFF state. A preventing element, which is responsive to the forward and reverse presence levers, is provided for preventing the motor from running, when the lawn mower is in neutral or a forward gear and neither the forward presence lever nor the reverse presence lever are in the ON state, and when the lawn mower is in a reverse gear and the reverse presence lever is not in the ON state.

Abstract: A control system is provided for a vehicle regulating engine speed during shifts so as to reduce driveline torque and shift shock. The control system includes separate microprocessor based engine and transmission controllers which communicate via a data link. When a shift is initiated, the transmission controller delays a period of time sufficient for the transmission to disengage the old gear ratio and then produces a CTSSPEED signal. The transmission controller continues to produce the CTSSPEED signal for a second period of time which corresponds to the time required for the transmission to engage the new gear ratio.The engine controller receives the desired engine speed signal and regulates engine speed into correspondence with the desired speed. During upshifts, the CTSSPEED signal is set to a speed which is a predetermined amount above the synchronization speed of the new gear for an upshift.

Abstract: A method and apparatus is provided for measuring detonation in an internal combustion engine. Vibration sensors located on the engine send signals through a filter which is turned to the cavity resonance of the engine's cylinders. The peaks and valleys of the filtered signals are detected and ratiometrically compared one with another to determine the magnitude of detonation. The detonation information may be used by an engine control to retard timing in response to a predetemined level of detonation.