GB2309287A - A pedal control for a vehicle - Google Patents

Description

1 A Pedal Control for a Vehicle 2309287 The invention relates to a pedal

control for a vehicle, in particular a lift truck, comprising a pair of 5 pedals which are coupled to each other in opposite senses.

It has become known to provide a double pedal control for lift trucks. The pedals are provided not only to generate a speed signal but also to determine the direction of travel. Accordingly one drive pedal is provided for control during forward drive and the other drive pedal is provided for control during backward drive.

DE 1530836 discloses a double pedal control wherein a gear is disposed on the pivot axis of each drive pedal, with the gears meshing with each other. One drive pedal is is connected via a linkage to a respective actuator of a hydraulic pump. Actuating the other pedal results in an opposite pivotal movement of the first mentioned drive pedal for generating a drive signal. As to the dimensional accuracy of the gears there are no particularly stringent requirements. However, if no particular measures are being taken, it cannot be ensured that displacements of the drive pedals about the same angle result in actuating signals of the same value (in opposite directions). A further disadvantage of the described interconnection of the drive pedals is that a predetermined space relationship is necessary in order to enable said interconnection via the gears. This may result in substantial space requirements.

DE 2814741 discloses an interconnection of pedals in a lift truck via a double-armed lever pivotally mounted to the vehicle, with arms connected to the pedals each being pivotally mounted via a ball joint to the doublearmed lever. Also this pedal control requires a predetermined arrangement of the double-armed lever between the pedals. This pedal control is not provided for a double pedal control but for a single pedal control, with two separable clutches being provided to enable drive control of the lift 2 truck via a single drive pedal with a drive direction selector.

DE 4445661 proposes to have both pedals act upon a lever pivotally mounted to the vehicle. The lever is used to generate an actuating signal mechanically. The points of engagement of the lever are selected such that when the pedals are pivoted for the same angle the lever is pivoted also for the same angle.

In prior art double pedal controls, depressing one of the pedals causes opposite movement of the other pedal for the same amount. This effect is ergonomically not particularly favourable. It results in "floating" of the feet. Reducing this effect detrimentally affects the sensitivity of the control due to reduced pedal strokes.

While it would be conceivable to actuate each pedal separately and to provide each pedal with its own drive signal generator, there would be the risk that both pedals inadvertently are operated simultaneously so that no clear signal would be generated. For this reason interlinking of both pedals is necessary.

The problem to be solved by the invention is to provide a pedal control for a lift truck which can be operated ergonomically and which prevents "floating" of the feet of the operator.

According to the present invention, a pedal control for a vehicle, in particular a lift truck, comprises a pair of pedals which are coupled to each other in opposite senses such that depressing one of the pedals provides a control signal for forward drive and depressing the other pedal provides a control signal for backward drive, the coupling of the pedals being arranged such that depressing one of the pedals for a predetermined first angle or distance results in raising the other pedal for a second angle or distance which is substantially less than said first angle or distance.

Preferably, the coupling of the pedals is of such a design that even maximal actuation of one pedal results 3 only in minimal raising of the other pedal. This interconnection of the pedals is ergonomically of advantage because the raised pedal does not bend upwards the respective foot. The stroke of the pedal may be substantial in order to allow for a sensitive control without resulting in a corresponding opposite stroke of the other pedal.

Said interconnection can be provided by various gear mechanisms.

Particularly preferred is a mechanical gear"mechanism which includes# according to one embodiment of the invention, a shaft to which a lever is pivotally mounted in the area of the pedals. The lever is pivotally mounted to the drive pedal via a linkage; the levers when in predetermined positions are mounted to the shaft such that is downward displacement of one pedal results in relatively reduced upward movement of the other pedal. The linkage may be guided by a fixed guide and may be mounted to the lever via an elongate hole, with the guides being arranged in mirror-like relationship. In this case the levers are positioned at the shaft in mirror-like relationship. The non-directional different transmission of movements is obtained by the fixed guide.

In another embodiment of the invention it is provided that a cam follower is connected to the pedals, which cam follower co-operates with a cam profile of a cam element, with the cam profiles of both cam elements being disposed in mirror-like relationship. one end of the cam element is fixedly pivotally mounted, and the other end is pivotally mounted to a lever which is non-rotatably connected to a coupling shaft such that the cam element may perform rotational movements. Preferably, the cam element along with a displacement lever and the lever non-rotatably f ixed to shaft provide a four-point-linkage such that the cam element may perform both rotational and translational movements. Preferably, the cam follower is a roller pivotally mounted to the pedal.

4 It is conceivable to have a signal generator associated with each pedal. For simplicity reasons, however, a single signal generator is preferred. The latter could be associated to a single pedal. Since, however, the pedal performs different length strokes on either side of the neutral position, the signal generator would have to be designed in an analogous manner. This, however, would be difficult to be achieved. Accordingly one embodiment of the invention provides that a signal generator is connected to the coupling shaft. The coupling shaft performs pivotal movements proportional to the stroke of the actuated pedal, with the direction of the pivotal movements depending on the respective actuated pedal. The signal generator may be formed for example by a potentiometer.

The invention will now be explained in more detail with reference to the accompanying drawings wherein:

Fig. 1 is a perspective view of a first embodiment of a pedal control of the invention; Fig. 2 is a perspective view of a further embodiment of a pedal control of the invention; and Fig. 3 shows schematically the pedal control of Fig.

2.

In Fig. 1 a pair of parallel spaced pedal levers 10, 12 are pivotally mounted via suitable bearings 14 and 16, respectively, to a vertical metal sheet 18 which is disposed below the bottom sheet (not shown) of a lift truck, such that the pivot axes of the pedal levers 10, 12 coincide.

To corners of the angular pedal. levers 10, 12 are mounted rods 20 and 22, respectively. Each rod 20, 22 is of fork-like shape in the lower area. Between the legs of each fork-like shape there is disposed a guide element 24 and 26, respectively, which is approximately L-shaped and is mounted so as to be fixed. The guide elements 24, 26 include L-shaped slots 28 and, respectively, 30. The slots 28, 30 are disposed in mirror-like relationship. Pins 32, 34 extend through the legs of the respective rods 20, 22.

As a result the pins 32 and 34 are guided by the slots 28 and 30, respectively. on either side of the legs of each of the rods 20 and 22, levers 36 and 38 and, respectively, levers 40 and 42 are fixedly mounted to a shaft 44, which is parallel to the above-mentioned pivot axis of the pedal levers 10, 12 and is also positioned below the abovementioned bottom sheet. The levers have elongate holes 46, 48 into which the pins 32, 34 respectively extend. Movements of the pins 32, 34 result in corresponding pivotal movements of the levers 36, 38 and, respectively, 40, 42 and accordingly rotational movements of the shaft 44. When for example the pedal 10 is depressed, the pin 32 moves along the substantially vertical portion of the guide slot 28, with the levers 36, 38 being pivoted so as to pivot the shaft for a predetermined amount. Coupled to the shaft 44 is a signal generator, not shown, for example a potentiometer, which provides a drive signal to the motor of the lift truck depending on the direction of rotation and the angle of rotation. The above-mentioned movement of the pedal 10 and, respectively, the shaft 44 results in raising of the pedal lever 12. Since the pin 34 moves in an approximately horizontal part of the guide slot 30, the pedal lever 12 is raised only slightly.

In Fig. 2 a bottom sheet 50 of a lift truck is shown by dashed lines; the approximately vertical legs of pedal levers 52, 54 including the foot surfaces extend through the bottom sheet. All other members shown in Fig. 2 are disposed below the bottom sheet 50. Mounted to the bottom sheet are support members 55, 56, 58, 60, 62 and 64. The support members 55, 56 support the pedal levers 52, 54 so that they are rotatable about the same axis of rotation.

The support members 58, 60 rotatably support a coupling shaft 66 to which a lever 68, and respectively, 70 is non-rotatably fixed. The levers 68, 70 have fork-like lower ends pivotally mounted about the rear end (in Fig. 2) of a cam element 72 and, respectively, 74. The front ends of the cam elements 72 and 74 are pivotally engaged by a link 76 6 and, respectively, 78 which are pivotally mounted to the support member 62 and, respectively, 64. The latter members form a four-point-linkage. This allows for rotational and translational movements of the cam element 72, 74 parallel to itself.

As may be seen the upper side of the cam elements 72, 74 includes a cam prof ile 80, 82 with which a roller 84 and, respectively, 86 co-operates. The roller is pivotally mounted to the approximately horizontal portion of the pedal lever 52, and, respectively, 54 by means of an inverted U-shaped support element 88 and, respectively, 90.

Mounted to shaft 66 is a further lever 92 which engages a (not shown) arm of a potentiometer 94. Depending on the displacement and the direction of rotation of shaft 66, the potentiometer 94 is operated to provide a control signal.

Fig. 3 shows schematically the arrangement of Fig. 2, with the same parts being designated by the same reference numerals. In Fig. 3 the pedal 54 is shown sideways while it is in two different positions, i.e. in the upper neutral position and in the lower depressed position. When the pedal is depressed, the roller 86 moves along a relatively steep portion of the cam profile 82 of the cam element 74. As a result the cam element 74 is moved to the right to the position shown by dashed lines so as to pivot the lever 70 about a respective angle resulting in rotation of the shaft 66. The potentiometer 94 provides a control signal. The shaft 66 pivots also the lever 68 of the other pedal 52 which is indicated in Fig. 3 by dash-dotted lines. Pivoting of lever 68 (as indicated in Fig. 3 by dash-dotted lines) results in corresponding movements of the cam element 72 and accordingly its cam profile 80. The associated roller 84 moves along the relatively flat portion of the cam profile 80 so that the drive pedal 52 is raised only slightly relative to the stroke of the drive pedal 54. When the drive pedal 52 is depressed, it is the drive pedal 54 which is raised only slightly, as described.

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Claims (9)

1. A pedal control for a vehicle, in particular a lift truck, comprising a pair of pedals which are coupled to each other in opposite senses such that depressing one of the pedals provides a control signal for forward drive and depressing the other pedal provides a control signal for backward drive, the coupling of the pedals being arranged such that depressing one of the pedals for a predetermined first angle or distance results in raising the other pedal for a second angle or distance which is substantially less than said first angle or distance.

2. A pedal control according to claim 1, in which each of the pedals is pivotally mounted by a linkage to a lever which is non-rotatably connected to a coupling shaft, the levers when in predetermined angular positions being provided at the shaft such that downward displacement of one pedal results in a respectively reduced upward displacement of the other pedal.

3. A pedal control according to claim 2, in which each of the linkages is guided by a fixed guide and is pivotally mounted simultaneously to the lever via an elongate hole, with the two guides being arranged in mirrorlike relationship.

4. A pedal control according to claim 2 or claim 3, in which each of the linkages comprises a rod pivotally mounted to the pedal and the lever.

5. A pedal control according to claim 1, in which a cam follower is connected to each of the pedals, which cam follower co-operates with a cam profile of a cam element, the cam profiles of the two cam elements being arranged in mirror-like relationship, one end of each of the cam elements being pivotally fixed, and the other end thereof being pivotally mounted to a lever non- rotatably fixed to a coupling shaft such that the cam elements may perform rotational movements.

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6. A pedal control according to claim 5, in which each of the cam elements along with a respective displacement lever and the respective lever non-rotatably fixed to shaft provides a four-point-linkage such that the cam elements may perform both rotational and translational movements.

7. A pedal control according to claim 4 or claim 5, in which each of the cam followers is a roller pivotally mounted to a respective one of the pedals.

8. A pedal control according to any one of claims 2 to 7, in which a signal generator is arranged to be actuated by the coupling shaft.

9. A pedal control substantially as hereinbefore described with reference to Figure 1, or Figures 2 and 3, of the accompanying drawings.