Interlock for lawnmower

Details Interlock for lawnmower Interlock for lawnmower

2000-07-20

2001-10-16

Pezzuto, Robert E. (Department: 3671)

Harvesters

Motorized harvester

With selective control of drive means

Reexamination Certificate

active

06301864

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to lawnmowers and, more specifically, to zero turn lawnmowers and a mechanical brake interlock for such mowers.
BACKGROUND OF THE INVENTION
Interlock systems for lawnmowers and specifically zero turn lawnmowers have been used in the past. Such prior arrangements have generally been electrically actuated, and have been expensive and yet not totally reliable.
SUMMARY OF THE INVENTION
The present invention provides a lawnmower having a chassis, an engine mounted to the chassis, a rotary cutting blade selectively rotated by the engine, and first and second drive wheels at least partially supporting the chassis and rotatable to cause movement of the chassis. A drive system is provided for each drive wheel and includes a control lever controlling the direction and speed of rotation of the drive wheel and having a neutral position where the drive wheel is not driven by the drive system. The lawnmower also includes a parking brake interconnected with the chassis and movable between an engaged position and a disengaged position to lock and unlock, respectively, the drive wheels.
The lawnmower may further include a brake sensor determining when the parking brake is in the engaged position, and a starting device for starting the engine. The brake sensor is a part of the starting circuit for the engine, and prevents the engine from starting when the parking brake is not in the engaged position. The starting device does not use sensors separate from the brake sensor to determine whether the control levers are in their neutral positions. Preferably, the brake sensor includes a switch in the form of a plunger.
The lawnmower may also include a linkage interconnecting the parking brake with the control levers. The linkage is moved into a non-interference position in response to the parking brake being disengaged, and is moved into an interference position in response to the parking brake being engaged. In the non-interference position, the linkage permits movement of the control levers from the neutral positions, and in the engaged position, the linkage resists movement of the control levers from the neutral positions.
Preferably, the lawnmower includes a biasing member biasing the linkage toward the interference position. The linkage preferably includes first and second interlock arms movable to hold the first and second control levers, respectively, in their respective neutral positions when the linkage is in the interference position. The interlock arms include ramped guide surfaces to guide the control levers to their respective neutral positions.
The linkage also may include a yoke mounted to the chassis for rotation with respect to the chassis. The interlock arms are fixed for rotation with the yoke, and the biasing member is interconnected with the yoke. The yoke includes a slot having at least one substantially closed end. The linkage preferably includes a finger extending into and movable along the slot to abut the closed end of the slot and move the interlock arms to the non-interference position against the biasing force of the biasing member. The finger disengages the closed end of the slot in response to the parking brake being moved toward the disengaged position.
The lawnmower may also include an over-center mechanism urging the parking brake toward the engaged position when it is in the engaged position, and toward the disengaged position when it is in the disengaged position. The over-center mechanism may also urge the yoke and interlock arms toward the non-interference position when they are in the non-interference position.


REFERENCES:
patent: 3766722 (1973-10-01), Kamlukin et al.
patent: 4310082 (1982-01-01), Elmy et al.
patent: 5335487 (1994-08-01), Murakawa et al.
patent: 6092617 (2000-07-01), White, III et al.

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