GB1578532A

GB1578532A - Link of adjustable length

Info

Publication number: GB1578532A
Application number: GB1924376A
Authority: GB
Original assignee: GEORGE ENG CO Ltd
Current assignee: GEORGE ENG CO Ltd
Priority date: 1977-08-01
Filing date: 1977-08-01
Publication date: 1980-11-05

Description

(54) LINK OF ADJUSTABLE LENGTH (71) We, GEORGE ENGINEERING COMPANY LIMITED, a British Company, of Carlyon Road, Atherstone, Warwickshire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a link of adjustable length and is particularly, but not exclusively, concerned with a link to be used as the upper link in a three-point linkage of a hydraulic lift mechanism of a tractor, especially an agricltural tractor.

To ensure that an implement already connected to the two lower links of a three-point linkage can be correctly connected by the upper link and that the implement is supported by the linkage at a required inclination, the upper link must be adjustable in length. It is also desirable that the adjustment in length shall be effected quickly to enable the coupling and uncoupling of an implement to be effected easily.

According to the invention, a link of adjustable length comprises a pair of telescopically-slidable members each having connecting means at the remote or outer end thereof for connection to one or other of a pair of mounting positions between which the link is to be connected, the inner member of said pair of members having a plurality of longitudinally-spaced groove portions extending peripherally around said inner member; locking means extending through the outer member of said pair of members, and a sleeve slidable longitudinally on said outer member between a locking position in which the sleeve engages the locking means and holds said locking means in engagement with one of the longitudinally-spaced groove portions and a release position in which the locking element is movable out of engagement with the groove portion by relative telescopic movement between said pair of members.

Conveniently, the locking means comprises a plurality of balls spaced apart around one of the groove portions in said inner member and each located in a through hole in said outer member and held in engagement with the groove portion by said sleeve when the sleeve is in its locking position, the sleeve having an inner peripheral surface shaped- to permit the balls to be pushed by one or other side of the groove portion on relative telescopic movement between said pair of members when the sleeve has been moved to its release position.

The sleeve is preferably biased by a spring into its locking position and is movable against the spring force into its release position.

The groove portion may be separately formed but conveniently each is a convolution of a continuous helical groove and the locking element is engageable in a convolution of the helical groove. Where the locking means comprises a plurality of circumferentially-spaced balls, the latter are positioned in respective holes in the outer member arranged with their centres spaced apart on a convolution of a helix having the same helix angle as the helical groove on the inner member.

By way of example, a link of adjustable length in accordance with the invention is now described with reference to the accompanying drawings, in which: Figure 1 is a side view of the link; Figure 2 is a section on the line II-II in Figure 1; Figure 3 is a section on the line III-III in Figure 2, and Figure 4 is an enlarged cross-section through an alternatively shaped groove that could be provided in the inner member shown in Figure 2.

Referring to Figures 1-3, the link comprises a pair of telescopically-slidable mem bers comprising an outer tubular member 1 and an inner cylindrical rod or tube 2. The outer or remote end of each member is welded to a coupling 3, 4 by which the members are respectively connected to mounting positions between which the link is to be connected. When the link is the upper link of a three-point linkage of a tractor hydraulic lift, the coupling would be connected to the tractor mounting and the coupling 4 would be connected to an implement. An outer end portion. adjacent the coupling 4 of the member 2 is formed with a hardened helical groove 5 which is part-circlllar in crosssection and of which each convolution forms one of the aforesaid longitudinally-spaced groove portions extending peripherally around the member 2. A hardened end portion of the tubular member 1 adjacent the grooved end of the mcmhcr 2 has a plurality of (e.g., six) radial through-holes 6 spaced apart cqui-distant around the member 1 and arranged on a convolution of a helix having the same helix angle as the helical groove 5 on the member 2. Eacll hole 6 contains a hardened ball 7 which is locatable in the groove 5 and when so located cxtends to the outer cylindrical surfaces of the member 1.

The member 1 has a knurlcd sleeve 8 slid ablc axially thereon and urged to the position illustrated in Figures 1 and 2 by a helical comprcssion spring 9 cngaging between the sleeve 8 and an abutmcnt collar 10 fitted on the member 1. The outward movement of the sleeve 8 is limitcd by a retaining clip 11 engaged in a groove in the member 1. The sleeve 8 has an inner cylindrical surface which engages the balls 7 in the illustrated position and it has an annular recess 12 into which the balls 7 are displacable when the sleeve is retracted to the right as viewed in Figures 1 and 2, against the force of the spring 9.

The position illus!ratcd in Figures 1 and 2 is the aforcsaid locking position in which the sleeve 8 holds the halls 7 in positions in which they protrude through the inner ends of the holes 6 and arc located in the groove 5 and thereby prevent any alteration in the length of the link between the centres of the couplings 3 and 4. The effective length of the link is determined by the convolution of the groove 5 in registration with the holes 6 when the sleeve 8 is released and allowed to be returned to the illustrated position by the spring 9.

When the effective length of the link is to be faltered, the sleeve 8 is retracted towards the collar 10 against the force of the spring 9.

This movement brings the recess 12 into registration with the balls 7 and thus on effecting relative telescopic adjustment of the members 1 and 2 in cither direction, the sides of the groove 5 will displace the balls 7 outwardly until they protrude into the recess 12. The members 1 and 2 are then free to be adjusted by relative telescopic movement to give the link a different effective length.

When the effective length is correct, the sleeve 8 is released and it will push the balls 7 into the portion of the groove 5 in registration with the holes 6 and the members 1 and 2 will again be locked from relative telescopic movement.

The part-circular cross-section of the groove 5 reduces the tendency of the groove to become clogged with muck or dirt and also makes it easily cleanable. However instead of the groove 5 being of part-circular crosssection, the grooves may have a flat side and a base when viewed in cross-section as shown at 5a in Figure 4.

Instead of the groove 5 or 5a being a continuous helix in which each convolution forms one of the aforesaid longitudinallyspaced groove portions, a plurality of separate longitudinally-spaced annular grooves may be formed on the member 2.

Instead of the balls 7 bearing directly in the groove 5 or Sa, or in separate grooves, a resilient part-annular or annular bearing element may be located in a peripherallyextending slot in the inner cylindrical surface of the member 1 and be urged into engagement with the groove 5 or Sa by the balls 7 located in the holes 6 in the member 1.

Instead of using the balls 7, equivalent locking elements of the other shapes arranged to be urged inwardly by a suitably shaped cam surface on the inside of the sleeve 8 may be provided.

Where the adjustable link is used as the upper link in a three-point linkage of an agricultural tractor, the implement would normally be connected first to the lower links of the three-point linkage and then, with the adjustable upper link already connected to the tractor mounting by the coupling 3, the sleeve 8 is rctracted and the link is extended until the coupling 4 is connected to the implement. The sleeve 8 may then be released. Alternatively, the tractor may be moved, the lift mechanism may be operated or the implement may be moved until the latter is at the required inclincation, that is the adjustable link has the correct length while the sleeve 8 is retracted. Then the sleeve 8 is released to lock the adjustable link at the correct length. Alternatively the adjustable link could be set to the required length and then be connected to the implement. When the adjustable link is to be disconnected from the implement, the sleeve is rctracted to enable the length to be altered while the link is being uncoupled.

WHAT WE CLAIM IS: 1. A link of adjustable length comprising a pair of telescopically-slid able members each having connecting means at the remote or outer end thereof for connection to one or

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. bers comprising an outer tubular member 1 and an inner cylindrical rod or tube 2. The outer or remote end of each member is welded to a coupling 3, 4 by which the members are respectively connected to mounting positions between which the link is to be connected. When the link is the upper link of a three-point linkage of a tractor hydraulic lift, the coupling would be connected to the tractor mounting and the coupling 4 would be connected to an implement. An outer end portion. adjacent the coupling 4 of the member 2 is formed with a hardened helical groove 5 which is part-circlllar in crosssection and of which each convolution forms one of the aforesaid longitudinally-spaced groove portions extending peripherally around the member 2. A hardened end portion of the tubular member 1 adjacent the grooved end of the mcmhcr 2 has a plurality of (e.g., six) radial through-holes 6 spaced apart cqui-distant around the member 1 and arranged on a convolution of a helix having the same helix angle as the helical groove 5 on the member 2. Eacll hole 6 contains a hardened ball 7 which is locatable in the groove 5 and when so located cxtends to the outer cylindrical surfaces of the member 1. The member 1 has a knurlcd sleeve 8 slid ablc axially thereon and urged to the position illustrated in Figures 1 and 2 by a helical comprcssion spring 9 cngaging between the sleeve 8 and an abutmcnt collar 10 fitted on the member 1. The outward movement of the sleeve 8 is limitcd by a retaining clip 11 engaged in a groove in the member 1. The sleeve 8 has an inner cylindrical surface which engages the balls 7 in the illustrated position and it has an annular recess 12 into which the balls 7 are displacable when the sleeve is retracted to the right as viewed in Figures 1 and 2, against the force of the spring 9. The position illus!ratcd in Figures 1 and 2 is the aforcsaid locking position in which the sleeve 8 holds the halls 7 in positions in which they protrude through the inner ends of the holes 6 and arc located in the groove 5 and thereby prevent any alteration in the length of the link between the centres of the couplings 3 and 4. The effective length of the link is determined by the convolution of the groove 5 in registration with the holes 6 when the sleeve 8 is released and allowed to be returned to the illustrated position by the spring 9. When the effective length of the link is to be faltered, the sleeve 8 is retracted towards the collar 10 against the force of the spring 9. This movement brings the recess 12 into registration with the balls 7 and thus on effecting relative telescopic adjustment of the members 1 and 2 in cither direction, the sides of the groove 5 will displace the balls 7 outwardly until they protrude into the recess 12. The members 1 and 2 are then free to be adjusted by relative telescopic movement to give the link a different effective length. When the effective length is correct, the sleeve 8 is released and it will push the balls 7 into the portion of the groove 5 in registration with the holes 6 and the members 1 and 2 will again be locked from relative telescopic movement. The part-circular cross-section of the groove 5 reduces the tendency of the groove to become clogged with muck or dirt and also makes it easily cleanable. However instead of the groove 5 being of part-circular crosssection, the grooves may have a flat side and a base when viewed in cross-section as shown at 5a in Figure 4. Instead of the groove 5 or 5a being a continuous helix in which each convolution forms one of the aforesaid longitudinallyspaced groove portions, a plurality of separate longitudinally-spaced annular grooves may be formed on the member 2. Instead of the balls 7 bearing directly in the groove 5 or Sa, or in separate grooves, a resilient part-annular or annular bearing element may be located in a peripherallyextending slot in the inner cylindrical surface of the member 1 and be urged into engagement with the groove 5 or Sa by the balls 7 located in the holes 6 in the member 1. Instead of using the balls 7, equivalent locking elements of the other shapes arranged to be urged inwardly by a suitably shaped cam surface on the inside of the sleeve 8 may be provided. Where the adjustable link is used as the upper link in a three-point linkage of an agricultural tractor, the implement would normally be connected first to the lower links of the three-point linkage and then, with the adjustable upper link already connected to the tractor mounting by the coupling 3, the sleeve 8 is rctracted and the link is extended until the coupling 4 is connected to the implement. The sleeve 8 may then be released. Alternatively, the tractor may be moved, the lift mechanism may be operated or the implement may be moved until the latter is at the required inclincation, that is the adjustable link has the correct length while the sleeve 8 is retracted. Then the sleeve 8 is released to lock the adjustable link at the correct length. Alternatively the adjustable link could be set to the required length and then be connected to the implement. When the adjustable link is to be disconnected from the implement, the sleeve is rctracted to enable the length to be altered while the link is being uncoupled. WHAT WE CLAIM IS:

1. A link of adjustable length comprising a pair of telescopically-slid able members each having connecting means at the remote or outer end thereof for connection to one or

other of a pair of mounting positions between which the link is to be connected, the inner member of said pair of members having a plurality of longitudinally-spaced groove portions extending peripherally around said inner member; locking means extending through the outer member of said pair of members, and a sleeve slidable longitudinally on said outer member between a locking position in which the sleeve engages the locking means and holds said locking means in engagement with one of the longitudinally-spaced groove portions and a release position in which the locking element is movable out of engagement with the groove portion by relative telescopic movement between said pair of members.

2. A link as claimed in Claim 1 in which the locking means comprises a plurality of balls spaced apart around one of the groove portions in said inner member and each located in a through hole in said outer member and held in engagement with the groove portion by said sleeve when the sleeve is in its locking position, the sleeve having an inner peripheral surface shaped to permit the balls to be pushed by one or other side of the groove portion on relative telescopic movement between said pair of members when the sleeve has been moved to its release position.

3. A link as claimed in Claim 1 or 2 in which the sleeve is biased by a spring into its locking position and is movable against the spring force into its release position.

4. A link as claimed in any preceding claim in which the groove portions are separately formed grooves.

5. A link as claimed in any one of Claims 1-3 in which each groove portion is a convolution of a continuous helical groove, the locking element being engageable in a convolution of the helical groove.

6. A link as claimed in Claim 2 in which each groove portion is a convolution of a continuous helical groove and the balls are positioned in respective holes in the outer member arranged with their centres spaced apart on a convolution of a helix having the same helix angle as the helical groove on the inner member.

7. A link of adjustable length constructed and arranged substantially as described herein and shown in Figures 1-3, or Figures 1-3 when modified in accordance with Figure 4, of the accompanying draw zings