Electrically released parking brake for zero turn radius mower

1. In a riding mower having a pair of independent drive wheels controlled by a corresponding pair of operator-manipulated drive levers said levers being movable independently of one another along parallel, fore-and-aft paths of travel between forward, neutral, and reverse drive modes and being movable outwardly away from one another to widespread positions when in the neutral mode, the improvement comprising:

at least one retaining mechanism operable when actuated to prevent rotation of at least one of said wheels; and

an electrical control circuit connected with said retaining mechanism in a manner to cause actuation of the retaining mechanism in response to the movement of at least one of the drive levers to said widespread position,

said retaining mechanism including a member movable toward and away from an actuated position and a spring yieldably biasing the member toward said actuated position,

said electrical control circuit including an electrically powered control device operable when energized to overcome the bias of said spring and release the retaining mechanism.

2. In a mower as claimed in claim 1 ,

said electrical control circuit further including a switch electrically connected with the control device in a manner to control energizing and dc-energizing of the control device,

said switch being disposed for operation by said at least one drive lever to dc-energize the control device when the drive lever is in the widespread position.

3. In a mower as claimed in claim 2 ,

further comprising a pivoting bracket for each lever and a link operably coupled with the bracket for controlling the speed and direction of rotation of a corresponding drive wheel,

each of said brackets supporting a corresponding drive lever for fore-and-aft movement of the lever along its path of travel,

said switch being mounted on the bracket associated with said at least one lever for movement therewith.

4. In a mower as claimed in claim 3 ,

each drive lever being pivotal supported on its bracket for movement toward and away from said widespread position.

5. In a mower as claimed in claim 1 ,

said control device including a pneumatically operated component operably coupled with the spring in a manner to overcome the bias of the spring as a result of air pressure applied to the component.

6. In a mow as claimed in claim 5 ,

said control device further including an electrically operated air pump operable when energized to supply air under pressure to said component,

said control device further including an air exhaust port openable when said at least one drive lever is in the widespread position to release air pressure on said component.

7. In a mower as claimed in claim 1 ,

further comprising an engine, a pair of hydraulic pumps operated by said engine, and a pair of reversible hydraulic motors connected hydraulically with respective ones of said pumps for driving corresponding ones of the drive wheels.

8. In a mower as claimed in claim 1 ,

further comprising guide structure defining a generally T-shaped guide slot for each of said drive levers,

each guide slot having a longitudinal portion extending parallel to the fore-and-aft path of travel of the lever and a transverse portion extending transverse to said path of travel,

each guide slot being disposed such that a drive lever is movable within the longitudinal portion of the slot during fore-and-aft movement of the drive lever along said path of travel and within the transverse portion of the slot during movement of the drive lever toward and away from said widespread position,

said transverse portion of the slot preventing fore-and-aft movement of the drive lever when the drive lever is in the widespread position.

9. In a mower as claimed in claim 1 ,

there being a retaining mechanism for each of said drive wheels.

10. In a mower as claimed in claim 1 ,

said retaining mechanism comprising a friction brake assembly.