Caster wheel locking system for walk-behind mower

[0001] This invention relates to grass mowing machines, and specifically to walk-behind mowers having rear driven wheels and front caster wheels.

[0002] Walk-behind mowers may be provided with caster wheels on the front of a mower deck and driven wheels on the rear of the deck. The caster wheels can pivot or steer with respect to the mower deck when the mower is turned, so that the operator is not required to raise the front or rear of the mower deck, or slide the wheels over the turf, during a turn. Front caster wheels reduce the effort required to maneuver the mower through a turn. Each front caster wheel may include an upright shaft which may be pivotally held within a cylindrical opening. As the mower makes a turn, the shaft pivots within the opening to allow the caster wheel to pivot. Thus, front caster wheels generally prevent turf from being scuffed or otherwise damaged during a turn of a walk-behind mower.

[0003] Some walk-behind mowers allow an operator to lock the front caster wheels for straight, lengthy cuts. Locking the front caster wheels also may help the mower maintain a straight cutting path along the side of a hill or bank by preventing the mower from sliding sideways down the slope. The caster wheel locking mechanisms may be mechanically actuated at or adjacent the pivoting shaft of each caster wheel. Additionally, during straight travel, the operator may engage a self-propel rear wheel drive mechanism using a lever or control located on or adjacent the mower handle.

[0004] When the operator needs to turn the mower, he or she may disengage the self-propel drive mechanism to stop the mower, and then disengage each of the caster wheel locking mechanisms. Otherwise, the mower does not obtain the full benefit of the caster wheels during a turn. After turning the mower, the operator may lock the casters again, and then engage the self-propel drive mechanism to resume a straight cutting path.

[0005] A caster wheel locking system is needed for a walk-behind mower that reduces the time and effort to engage the front caster wheels during straight cuts, and disengage the front caster wheels during turns. A caster wheel locking system is needed that increases productivity by allowing engagement and disengagement of the front caster wheels without stopping the mower.

[0006] A caster wheel locking system for a walk-behind mower reduces mowing time and effort by automatically engaging the front caster wheels during straight cuts, and disengaging the front caster wheels during turns. The caster wheel locking system increases productivity by engaging and disengaging the front caster wheels without stopping the mower. The caster wheel locking system includes a caster wheel lock on each front caster wheel. Each caster wheel lock can lock and align the front caster wheels in a forward direction if the traction drive bar is in the forward drive position, and can unlock the front caster wheels to allow them to steer freely if the traction drive bar is in the neutral position. The traction drive bar is connected to the handle and can move between a neutral position and a forward drive position in which the pair of rear wheels rotate to propel the mower forward.

[0012] In a first embodiment shown in FIGS. 1-5, walk-behind mower 100 is provided with handle 102 attached to mower deck 105. The mower deck is supported by a pair of front wheels 104 and a pair of rear wheels 106. An internal combustion engine 110 or other power source may be positioned on the mower deck for rotating a vertically aligned spindle and a mower blade turning under the deck.

[0013] In one embodiment, rear wheels 106 may be self propelled by a drive mechanism connected to the engine and controlled by the operator using traction drive/self-propel bar 114. The traction drive/self-propel bar may be hinged or slidably mounted to handle 102, and the operator may use the bar to propel the mower forward and control the drive speed of the rear wheels. The bar may be biased to a neutral position, and the operator may pivot the bar out of the neutral position to a range of forward drive positions corresponding to the position or angle of the bar relative to the handle. Additionally, the mower may include an operator presence bar 116 hinged to handle 102 in a manner requiring the operator to grip the bar in an operating position to avoid killing the engine and halting rotation of the mower blade.

[0014] In one embodiment, each front wheel may be rotatably mounted to a wheel mount 132 at the front end of a forward extending arm 126 attached to the mower deck. A caster wheel lock 112 may be provided between each wheel mount 132 and the forward extending arm 126. Each caster wheel lock 112 is part of a caster wheel locking system operable with caster control lever 120 pivotably mounted in lever housing 121 on handle 102. The operator may move caster control lever 120 between a locked position, an automatic position, and an unlocked position. The three different positions are shown in FIGS. 3-5 and are described below.

[0015] In one embodiment, bowden cable 122 may connect each caster wheel lock 112 to caster control lever 120. Each caster wheel lock may include an upright shaft 108 mounted in cylindrical bore 124 extending vertically through each caster wheel lock housing 118. Each upright shaft may have an opening or hole extending therethrough, which may be engaged by a spring loaded caster wheel locking pin 128.

[0016] In one embodiment, caster control lever 120 determines the position of cable 122 which determines the position of the spring loaded caster wheel locking pins at each of the front caster wheels by increasing or decreasing the tension on cable wire 133. An operator can quickly and easily change settings of the front caster wheels by moving lever 120 between a locked tracking position in which the front caster wheels are aligned in the forward direction, or an unlocked continuous free spin position. Additionally, an operator can move caster control lever 120 to an automatic position where the front caster wheels are locked only if traction bar 114 is engaged. In the automatic position, while the traction bar is engaged, there is reduced tension on linkage 136 (which may be a rod or cable) and wire 133. However, in the automatic position, while the traction bar is disengaged, there is increased tension on linkage 136 and wire 133, extracting pins 128 from the front caster wheels. As a result, if the traction bar is disengaged, the caster wheels are unlocked allowing them to steer around a turn. Traction bar 114 may be mechanically linked by a cable 136 which is fastened to the upper end of the bowden cable housing.

[0017] In one embodiment, spring loaded caster wheel locking pins 128 are mounted in each caster wheel lock housing. Spring 130 is provided around each pin to bias the pin into an opening 138 or hole in each upright shaft 108, and bowden cable 122 connected between the pin and caster control lever 120 is used by the operator to pull the pins away from the openings in the upright shafts via mechanical link 134. For example, the mechanical link at the lower end of the wire 133 may be a hook that engages the spring loaded caster wheel locking pin.

[0018] In one embodiment, bowden cable 122 is branched to each of the caster wheel locks on the left and right front caster wheels with a “T” or “Y” junction that provides equal force to each cable end.

[0019] As shown in FIG. 3, if the operator moves the caster control lever 120 to the locked or tracking position, the bowden cable attached to the lever does not exert enough tension on the inner cable, and does not displace the inner cable sufficiently, to pull the spring loaded caster wheel locking pins out from openings 138 in the upright shafts. As a result, the spring loaded caster wheel locking pins remain in the openings to prevent the upright shafts from pivoting in the cylindrical bore. The pins hold the upright shaft in the locked or tracking position so that the wheels are aligned to rotate forwardly, and cannot steer.

[0020] In FIG. 4, the caster control lever is in the automatic position. In the automatic position, bowden cable 122 pulls the spring loaded pins out of openings 138 in the upright shafts only if traction drive bar 114 is released to the neutral position. At that time, while the traction drive bar is released, the front caster wheels can pivot or steer. If the traction drive bar is engaged to drive the rear wheels forwardly, the bowden cable tension is released and allows the spring loaded pins to re-enter the openings. At that time, the front caster wheels are locked and aligned in the forward tracking position. Thus, the automatic position aligns the front caster wheels to track straight as the operator engages the traction drive bar, or steer freely as the operator disengages the traction drive bar.

[0021] FIG. 5 shows the caster control lever in the unlocked position. In the unlocked position, the bowden cable attached to the caster control lever pulls the spring loaded caster wheel locking pins out and away from openings 138 in the upright shafts so the caster wheels can freely steer. The spring loaded pins are not in the openings in the upright shafts, so the shafts can pivot within cylindrical bore 124 and the front caster wheels can pivot or steer freely.

[0022] Having described a preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.