Harvesters – Motorized harvester – With selective control of drive means
Reexamination Certificate
2001-09-25
2003-09-30
Pezzuto, Robert E. (Department: 3671)
Harvesters
Motorized harvester
With selective control of drive means
Reexamination Certificate
active
06625963
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to garden tractors, riding lawnmowers, and the like, specifically to means for preventing a mower from being shifted into reverse when the mower deck is operating, in conformance with certain proposed industry standards.
Riding mowers, including most lawn tractors and garden tractors, include potentially dangerous rotating blades which comprise part of the mower deck and which may cause injury to the operator or another person. New industry standards are being considered which are aimed toward the prevention of such injuries, and safety devices are now being, or will likely be, included on riding mowers in support of these goals. Various types of these devices prevent operation of the mower deck while the mower is being reversed, or prevent the mower from being reversed while the mower deck is in operation.
Some of these previous devices will automatically shut off the engine if the mower is reversed while the mower deck is engaged. Such action is inconvenient since the operator would then need to restart the mower. Often, an operator will unintentionally put the mower in reverse with the mower deck engaged, such as when the operator realizes that he just passed an area to be mowed and, without thinking, shifts the mower into reverse to mow that area, consequently killing the engine.
Other previous safety devices include an engine kill relay with an override switch which allow the operator to reverse the mower with the mower deck operating only when the override switch is engaged simultaneously with the reverse gear being selected (U.S. Pat. No. 6,109,010). However, if the override switch is not engaged, shifting into reverse causes the engine to be shut off through the kill relay. In operation, the current path between a kill relay and a ground terminal is terminated if a reverse switch is opened and the PTO switch is turned on, thereby terminating engine operation. However, if the override switch is actuated, then as long as the PTO switch is turned on, current will be maintained between the relay and ground. Thus, the override switch eliminates the capability of breaking the current path and terminating engine operation if the mower is shifted into reverse with the mower deck operating, thereby allowing for potential unsafe operation of the mower. Further, such systems require operator manipulation of multiple controls in order to actuate the override switch before shifting into reverse.
Other safety devices require the operator to depress and hold down a button, or pull out a device, while shifting the mower into reverse, thereby requiring simultaneous manipulation of multiple controls by the operator to both deactivate the safety device and shift the mower into reverse. These devices are thus inconvenient and may allow potentially unsafe operation of the mower.
While these previous devices eliminate the possibility of an operator unintentionally shifting the mower into reverse since the operator would need to manipulate several controls to do so, these devices are rather inconvenient to operate and not intuitively operable by an operator unfamiliar with such controls. Further, potentially unsafe mower operation may be accommodated through such override devices.
Other attempts to address the issue of preventing the mower from being reversed with the mower deck operating include the use of mechanical safety interlocks which rotate an arm into a blocking position in the shifting rod slot when the mower deck is engaged (U.S. Pat. No. 3,984,967), and thereby preventing the operator from shifting the mower into reverse. Such devices are cumbersome and expensive.
Still other attempts to address this issue include an electrical interlock system in which an electric circuit and switch are opened to de-energize an electromagnetic clutch to automatically disconnect the mower drive when the mower is shifted into reverse (U.S. Pat. Nos. 3,999,643 and 6,026,634). Automatically disconnecting power to the mower deck also inconveniences the operator, who would need to reconnect power to the mower deck. Additionally, such systems are applicable only to mowers having electromagnetic blade engagement clutches, not mechanical clutches such as, for example, a belt tensioner. Thus, such systems may not be used on mowers in which the mower deck is engaged through a non-electrical clutch.
It is desirable to provide a device by which the mower is prevented from being reversed while the mower deck is operating without shutting off the engine, and to provide such a device which may be incorporated into all riding mowers, not just those in which the mower deck is electrically engaged.
SUMMARY OF THE INVENTION
The present invention provides a lawn mower including a frame, an engine having an electrical system and attached to the frame, a mower deck assembly having a rotating blade and connected to the frame, the blade selectively engaged with the engine, a reversible transmission driven by the engine and having a shift mechanism having a forward and a reverse position, a switch in electrical communication with the electrical system and mower deck assembly, and a solenoid attached to the transmission and in electrical communication with the switch and having a plunger. The switch is in a first position when the blade is in engagement with the engine and in a second position when the blade is out of engagement with the engine. The plunger is in an extended position when the switch is in its first position wherein movement of the shift mechanism into its reverse position is blocked by the plunger, and is in a retracted position when the switch is in its second position wherein movement of the shift mechanism into its reverse position is not blocked by the plunger.
The present invention further provides a reversible transmission for a lawn mower including a housing, an input shaft and an output shaft rotatably supported in the housing, an operator controlled shift mechanism having a forward position and a reverse position, and a solenoid connected to the housing and having a plunger. The plunger has an extended position wherein movement of the shift mechanism into its reverse position is blocked by the plunger, and a retracted position wherein movement of the shift mechanism into its reverse position is not blocked by the plunger.
The present invention also provides a reverse shift lockout system for a lawn mower including an engine, a transmission having a selectively entered reverse condition and a selectively entered forward condition and driven by the engine, an electrical source, a mower deck assembly selectively engaged with the engine, a switch in electrical communication with the electrical source and the mower deck assembly and being in a first position when the mower deck assembly is engaged and in a second position when the mower deck assembly is not engaged, and means in communication with the switch for preventing the transmission from entering its reverse condition when the switch is in its first position and permitting the transmission to enter its reverse condition when the switch is in its second position.
The present invention also provides a method of preventing an operator from placing a mower in reverse when its mower deck is operating, including extending the solenoid plunger in response to the mower deck being engaged, blocking movement of a transmission shift mechanism into reverse with the extended solenoid plunger, whereby the mower cannot be placed in reverse with the mower deck being engaged, and retracting the solenoid plunger in response to the mower deck being disengaged, whereby the mower may be placed in reverse.
The present invention also provides a lawn mower including a frame, an engine having an electrical system and attached to the frame, a mower deck assembly connected to the frame and having a rotating blade being selectively engaged with the engine, a reversible transmission driven by the engine and having a shift mechanism having a forward position and a reverse position, and means for preventing the shift
Baker & Daniels
Pezzuto Robert E.
Tecumseh Products Company
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