GB2147088A

GB2147088A - Hand lever assembly

Info

Publication number: GB2147088A
Application number: GB8422295A
Authority: GB
Inventors: John Pontefract
Original assignee: Case Poclain Corp Ltd
Current assignee: Case Poclain Corp Ltd
Priority date: 1983-09-08
Filing date: 1984-09-04
Publication date: 1985-05-01
Also published as: GB8422295D0; GB8324124D0; GB2147088B

Abstract

A control lever 43 is held disengaged by two separate means. The lever 43 is so arranged that it must be moved over-centre into its disengaged position. Additionally, the lever 43 is automatically latched to a fixed member 52, 42 as it moves into its disengaged position, deliberate manual release of the latch 51 being necessary before the lever 43 can be moved back over-centre into its engaged position. Specifically used as the clutch control lever on an agricultural tractor. <IMAGE>

Description

SPECIFICATION Hand lever assembly This invention relates to a hand lever assembly, and particularly to a hand lever assembly for controlling a mechanism which requires to be held safely inoperative such as a power take-off clutch of an agricultural tractor or the like.

The object of the invention is to provide a hand lever assembly which is held in its disengaged position by two separate means.

According to the invention, a hand lever assembly for controlling a disengageable mechanism comprises fixed support bracket means, a hand lever pivotably mounted at one of its ends near one end of said means for movement between an engaged position and a disengaged over-centre position, a control member slideable towards and away from the pivot of said lever near the other end of said means, a link pivotally connected at one of its ends to a point between the ends of said lever and at its other end to said member, and a latch mounted on said lever and engageable with a detent fixed to said one end of said means when said lever is in its disengaged over-centre position.

A preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings of which: Figure 1 is a sectional side elevation of a transmission and power take-off friction clutch assembly of an agricultural tractor; Figure 2 is a side elevation shown partly in section of a hand lever assembly for controlling the power take-off friction clutch of the tractor; and Figure 3 is a view in the direction of the arrow 3 in Fig. 2 Referring now to Fig. 1, a known transmission and power take-off friction clutch assembly of an agricultural tractor disclosed in U.K.Patent No. 2043805 is housed within the tractor frame (a partition of which is shown at 9) and includes a transmission clutch plate 10 mounted on splines 11 on a sleeve 1 2 constituting the input shaft of the tractor's transmission gearing, and a power take-off clutch plate 1 3 mounted on splines 14 on a shaft 1 5 extending through the sleeve 1 2 and driving a power take-off shaft by way of two-speed gearing. The transmission gearing, power take-off shaft and twospeed gearing are not shown.The transmission clutch plate 10 is engageable between a pressure plate 1 6 and a driving surface in a clutch casing 1 7 rigidly secured to the tractor's flywheel 18, and the power take-off clutch plate 1 3 is engageable between a pressure plate 1 9 and a driving surface on the flywheel 1 8. The clutch plates 10 and 1 3 are engaged by the combned action of a diaphragm spring 20 and of a plurality of circumferentially-disposed helical compression springs 21 interposed between the pressure plates 1 6 and 1 9. The transmission clutch plate 10 is disengageabie by the action on studs 22 secured to the pressure plate 1 6 of pins 23 carried by levers 24 which are pivotable on the casing 1 7 by a yoke plate 25 moveable axially by a bearing 26 mounted on a collar 27 slideable on a fixed tubular member 28 by a fork 29 secured on a cross-shaft 30. Said cross-shaft projects from the tractor frame and has secured on one of its projecting ends a lever operable hydraulically by a conventional foot pedal, said lever and pedal being not shown.The power take-off clutch plate 1 3 is disengageable independently of the transmission clutch plate 10 by the action of links 31 pivotally connected between the pressure plate 1 9 and levers 32 which carry studs 33 and are pivotable on the casing 1 7 by a ring 34 journalled on a bearing 35 mounted on a collar 36 slideable on the collar 27 by a fork 37 secured on a cross-shaft 38 projecting from the tractor frame and having a lever 39 secured on one of its projecting ends.

Referring now to Figs. 2 and 3, the lever 39 is operated as hereinafter described by a hand lever assembly which includes a first support bracket 40 of channel-shaped crosssection adapted to be fixed to the tractor's cab floor 41 and a second support bracket 42 of channel-shaped cross-section fixed in an upstanding but forwardly-inclined position to the first support bracket 40. A hand lever indicated generally at 43 has a main portion 44 of channel-shaped cross-section with a hand grip portion 45 formed of round section tubing welded to it.The hand lever 43 is pivotably mounted at its end remote from the hand grip portion 45 on a horizontal bolt 46 which extends transversely of the tractor near the upper end of the second support bracket 42, so as to be moveable forwardly and downwardly from an upstanding but forwardlyinclinded clutch disengaged position shown in full lines in Fig. 2 to a clutch engaged position shown in broken lines in Fig. 2, and vice versa. A control member comprises a pin 47 slideable in a pair of slots 48 which are formed in the sides of the second support bracket 42 near the lower end thereof and extend radially of the pivot bolt 46 of the hand lever 43.A link 49 is pivotally connected at one of its ends to a pin 50 disposed between the ends of the hand lever 43 and at its other end to the pin 47, and is curved so as to clear the pivot bolt 46 of the hand lever 43 when said lever is in its disengaged position. Said position is arranged to be slightly overcentre; that is to say, when the hand lever 43 is in its disengaged position the pin 50 connecting the link 49 to said lever is disposed slightly on that side opposite said lev er's engaged position of the plane containing the centre-lines of the pivot bolt 46 and the pin 47. A latch 51 is pivotably mounted on the hand lever 43 and is engageable, when said lever is in its disengaged position, with a detent 52 fixed to the upper end of the second support bracket 42.The latch 51 is pivotally connected to one end of a rod 53 which has fixed to its other end a button 54 disposed at the free end of the hand grip portion 45 of the hand lever 43 within a shroud 55 shielding said button from accidental depression. A helical compression spring 56 for urging the latch 51 into its engaged position surrounds a zone of the rod 53 and is confined between a collar 57 welded on said rod and an abutment plate 58 welded within the main portion 44 of the hand lever 43, the plate 58 having a slot 59 accommodating lateral as well as longitudinal movement of the rod 53 as the latch 51 pivots on said lever. The latch 51 is so shaped as to engage the detent 52 automatically when the hand lever 43 is moved into its disengaged position.

Referring now to all three Figs. of the drawings, the pin 47 forming the control member of the hand lever assembly is operatively connected to the lever 39 by a Bowden cable (Registered Trade Mark). One end of the outer casing 60 of said cable is mounted within a sleeve 61 which passes through and is welded to the first support bracket 40 and projects through a hole 62 in the cab floor 41, and the other end of the outer casing 60 is mounted on a bracket 63 which is secured to the tractor frame in fixed relationship to the friction clutch assembly. One end of the wire 64 of the Bowden cable (Registered Trade Mark) is connected to a fork 65 pivotally connected to the pin 47, and the other end of the wire 64 is connected to a rod 66 which is adjustably secured to a fork 67 pivotally connected to the lever 39.A flexible bellows 68 is disposed between said one end of the outer casing 60 and a sleeve 69 surrounding the wire 64 and contacting the fork 65, and a flexible bellows 70 is disposed between said other end of the outer casing 60 and the rod 66.

In operation, the power take-off friction clutch is held disengaged by two separate means so as better to avoid accidents due to its inadvertent engagement-firstly by the pull on the wire 64 of its own engagement springs 20 and 21 which holds the hand lever 43 in its disengaged position due to said position being slightly over-centre, and secondly by the latch 51 which automatically engages the detent 52 when said lever is moved into said position. The clutch is engaged by depressing the button 54 with the thumb to release the latch 51 and then moving the hand lever 43 forwardly and downwardly. Disengagement of the clutch is effected by-moving the hand lever 43 back into its disengaged position against the pull of the clutch engagement springs 20 and 21.

Claims

1. A hand lever assembly for controlling a disengageable mechanism comprising fixed support bracket means, a hand lever pivotably mounted at one of its ends near one end of said means for movement between an engaged position and a disengaged over-centre position, a control member slideable towards and away from the pivot of said lever near the other end of said means, a link pivotally connected at one of its ends to a point between the ends of said lever and at its other end to said member, and a latch mounted on said lever and engageable with a detent fixed to said one end of said means when said lever is in its disengaged over-centre position.

2. A hand lever assembly according to claim 1, wherein the latch is spring-engaged and manually released by a button disposed at the other end of said lever.

3. A hand lever assembly according to claim 2, wherein the button is disposed within a shroud shielding it from accidental depression.

4. A hand lever assembly according to claim 2 or claim 3, wherein the latch is pivotably mounted on said lever and pivotally connected to one end of a rod which has the button fixed to its other end, a helical compression spring for urging the latch into its engaged position being confined between a collar fixed on the rod and an abutment fixed on said lever, the abutment having a slot accommodating lateral as well as longitudinal movement of the rod as the latch pivots on said lever.

5. A hand lever assembly according to any one of the preceding claims, wherein the control member is a pin slideable in a slot and adapted to be operatively connected to the mechanism by a Bowden cable (Registered Trade Mark).

6. A hand lever assembly according to any one of the preceding claims, wherein the link is curved so as to clear the pivot of said lever when said lever is in its disengaged over-centre position.

7. A hand lever assembly according to any one of the preceding claims, wherein the mechansim is a power take-off clutch of an agricultural tractor or the like.

8. A hand lever assembly for controlling a disengageable mechanism constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.