GB2241049A - Combined brake and clutch operation in pedestrian-controlled mowers - Google Patents

Abstract

The mower has a separate brake for each driven wheel (10,12) operated by a pair of handlebar levers (22) via bellcranks (26) which are biassed to the brakes on position by springs (32). The clutch is actuated by a lever and rod (16,40) which are biassed to the disengaged position by a spring (20) which is weaker than either spring (32). A connection is provided between the brake bellcranks (26) and the clutch rod (40) such that when both brakes are applied the clutch is automatically disengaged, thus obviating the need for a manual clutch lever. In Fig. 1, the connection comprises a channel member (38) fast with the clutch rod (40) which receives lateral extension rods (34,36) fast with the bellcranks (26). In a modification (Fig. 2) the clutch rod (40) terminates in an eye which receives a single rod extending between the bellcranks (26). <IMAGE>

Description

PEDESTRIAN CONTROLLED MOWERS This invention relates to pedestrian controlled mowers which comprise a pair of driven wheels located on a common axis which is usually behind the cutter system.

Front wheels which may be castors, or a roller may be located on the opposite side of the cutter system. For the purpose of manoeuvreing, for example in mowing close to trees or around obstacles, it is desirable to be able to immobilise either wheel so as to pivot around that wheel. It is also necessary to be able to de-clutch the drive from the wheels.Hitherto this has usually required three different controls, that is a left wheel brake, a right wheel brake, and a clutch. or a rider controlled mower one hand and two foot (or vice versa) controls is possible and convenient, but for a pedestrian controlled mower this is more difficult and usually it has been found necessary to have individual hand operated brake levers with override catches so that they can be locked on, allowing a third lever for clutch operation to be used by either hand after locking the brake in place.

But this complicates construction and use, and in addition necessitates the pedestrian controller removing one hand from the steering handlebar whilst the clutch is operated. In an emergency, stopping the unit as aforementioned is not a natural reaction. If the brakes are applied before the clutch is disengaged unnecessary stresses are applied to the drive and braking mechanism.

If on the other hand the clutch is disengaged first, then the stopping distance is extended. In either case operation in complete safety -is impair'ed. The object of the invention is-t-o solve this problem.

According to the invention a pedestrian controlled mower comprises a drive motor, a clutch and a pair of driven wheels, said clutch being mechanically maintained in engagement against a first resilient means tending to disengage it; a separate brake for each wheel, each brake being urged by a corresponding second or third resilient means to an off (unbraked) condition; there being a physical connection between each brake and the clutch when the brakes are off, and the arrangement being such that operation of the brakes withdraws the connection from the operated brake to the clutch, so that when both brakes are applied the clutch is automatically disengaged by the first resilient means.

The first resilient means may act in the opposite direction to the second and third resilient means, and be weaker than either of the second and third resilient means.

The physical connection may comprise a tie bar extending between a pair of levers, one in each brake system, and the clutch being operated by a rod coupled to the tie bar at a midpoint. Movement of either lever, when the corresponding brake is applied, is accompanied by swinging of the bar about the midpoint without clutch disengagement, but operation of both levers causes displacement of the midpoint and of the clutch rod.

Preferably however the physical connection comprises a pair of separate lateral extensions, one from each lever in the respective brake systems, said extensions being coaxial in an at-rest state, and saic extensions being received in an abutment member carried by the clutch rod so that the resilient means maintain contact between the said extensions and the abutment, operation of either brake overcomes the corresponding resilient means to withdraw the corresponding extension from the abutment, and withdrawal of both extensions allows the first resilient means to operate the clutch.

The invention is more particularly described with reference to the accompanying drawings wherein: rigure 1 is a fragmentary, perspective and somewhat- diagrammatic view of a preferred embodiment, with parts of the mower omitted for clarity; and Figure 2 is a similar view of a second embodiment.

Turning first to Figure 1, the mower shown therein has a pair of driven wheels 10,12 mounted coaxially and driven for example by hydrostatic means from an engine, not shown. The clutch, also not shown, includes pulley 14 mounted on a first bellcrank link 16 pivoted at 18 and the crank is urged to pivot clockwise by spring 20 for clutch disengagement. Other clutch mechanisms such as the known cone or disc types could be operated in similar fashion.

Each brake operating system comprises a handlebar lever 22, a tie rod or wire 24 and a bellcrank lever 26 pivoted at 28 so that clockwise movement caused by the lever 22 displaces the final link 30 to apply the brake.

The lever 26 is in each case held in the brake off position by a corresponding spring 32.

The mechanical connection between the clutch and brakes is provided by lateral extension rods 34 36 fast with the respective bell cranks 26 and which in the rest condition are coaxial. These rods extend towards one another and are received in a channel-shaped abutment member 38 fast with clutch rod 40 pivoted to the bell crank 16.

The springs 32 are individually stronger than the spring 2G. Either brake is applied by the corresponding lever 22 and the relatively strong spring is overcome by the mechanical advantages afforded by the lever system.

In the course of the bell crank movement the lateral extension 34 or 36 is withdrawn from the abutment member: conveniently the channel-shaped abutment member has side walls of sufficient length so as to retain the lateral extension therebetween in the withdrawn position, so as to maintain alignment of the parts. Withdrawal of either rod does not affect the clutch position because the remaining extension is spring held with sufficient force to overcome the clutch spring. When both rods are withdrawn because both brakes are applied the clutch spring is free to displace the pulley 14 and disengage the clutch.

Turning now to Figure 2, the arrangement is generally similar except that here a single rod 44 extends between the two bell crank levers in the brakes system and the clutch rod 40 has an eye 46 looped about rod 44. Movement of either brake bellcrank in the clockwise direction for brake operation pivots the rod 44 in the eye which has the affect of pivoting the other (non-operated) brake crank in the opposite direction, unless lost motion is provided in the system for example by using slots to connect the bellcrank to the operating parts. However, the clutch remains engaged unless both brakes are applied when the rod 44 will move bodily for this purpose. It will be appreciated that the movement of the rod 44 is complex, since the end connected to the one brake which is operated moves arcuately about the bell crank pivot and the other end of the rod necessarily moves likewise but in the opposite direction. Rod 40, at this time remains still, so rod 44 actually moves in two planes relative to the eye 46.

The brakes may be externally contracting band brakes as shown in Figure 2.

Claims (6)

1. Q pedestrian controlled mower comprising a drive motor, a clutch and a pair of driven wheels, said clutch being mechanically maintained in engagement against a first resilient means tending to disengage it; a separate brake for each wheel, each brake being urged by a corresponding second or third resilient means to an off (unbraked) condition; there being a physical connection between each brake and the clutch when the brakes are off, and the arrangement being such that operation of the brakes withdraws the connection from the operated brake to the clutch, so that when both brakes are applied the clutch is automatically disengaged by the first resilient means.

2. A mower as claimed in Claim 1 wherein the physical connection comprises a tie bar extending between a pair of levers, one in each brake system, and the clutch is operated by a rod coupled to the tie bar at a midpoint, so that movement of either lever when the corresponding brake is applied is accompanied by swinging of the bar about the midpoint, but operation of both levers causes displacement of the midpoint and clutch rod.

3. A mower as claimed in Claim 1 wherein the physical connection comprises a pair of lateral extensions from levers in the respective brake systems, said extensions being coaxial in an at-rest state, and said extensions being received in an abutment member carried by the clutch rod so that the second and third resilient means maintain contact between the said extensions and the abutment, but operation of either brake overcomes the corresponding resilient means to withdraw the corresponding extension from the abutment, and when both are withdrawn the first resilient means disengages the clutch.

4. A pedestrian controlled mower as claimed in any preceding claim provided with handlebars carrying pivoted brake operating levers which are linked to the respective brakes by a mechanical system including a pivoted bellcrank in each system and the said second and third resilient means urge the bellcranks to the unbraked condition.

5. A pedestrian controlled mower as claimed in any previous claim wherein the clutch operating system comprises a bellcrank pivoted for clutch operation.

6. A pedestrian controlled mower substantially as described with reference to Figure 1 or Figure 2 of the accompanying drawings.