CONTROL CABLE ADJUSTER DEVICE

Abstract: A control cable adjuster device (Figure 4) for connection into and tensioning of a control cable run includes a termination member rod 13 extending into a tubular housing 10 through a locating means or insert 11. Collet means 14 biassed by a circumferential spring 17 are positioned in the insert 11 and are formed with 90° triangular profile serrations 31 co-acting with serrations 32 on the rod 13. A helical spring 19 acting between the insert 11 and a collar 21 on the rod 13 acts to induce tension in the cable run. Engagement of part frusto-conical faces 15 on the collet means 14 with a frusto conical face 16 on the insert 11 acts to urge the collet means into locking engagement with the rod 13. An axially movably release tube 25 with a frusto-conical head 29 co-acts with part frusto-conical faces 27 on the collet means and is actuable to displace the collet means radially outwardly to permit compression of the spring 19 by tensioning the rod 13. A clip 33 serves to hold the rod in the extended position during connection of the device into the cable run and is released to place the device in service.

Description: This invention relates to control cable adjuster devices and, more particularly to devices insertable into control cable runs either at intermediate locations or adjacent terminations to provide tensioning of the cable run, such as in foot pedal operated cable controlled brake systems or clutches in automobiles. In US A-4 378 713 there is disclosed a control cable adjuster device including a tubular housing having at one end a first anchorage connectable into a cable run and at the other end locating means for a termination member movably extending co-axially of the tubular housing between a position fully retracted into, and a position fully extended from, the tubular housing, the termination member being formed on the surface thereof with circumferential serrations engageable with collet means and, on the end thereof remote from the tubular housing, a second anchorage connectable into the cable run. By the present invention, the device includes first resilient means biassing the termination member toward the position fully retracted into the tubular housing, the collet means are located in the locating means and formed on radially inner faces with serrations adapted to co-act with the serrations on the termination member, second resilient means biassing the collet means radially inwardly, a first frusto-conical surface in the locating means at the axially inner end thereof arranged to co-act with first, part frusto-conical, surfaces on the collet means such that relative axial movement of the collet means axially inwardly urges the collet means radially outwardly and a second frusto-conical surface in the locating means at the axially outer end thereof arranged to co-act with second, part frusto-conical, surfaces on the collet means such that relative axial movement of the collet means axially outwardly urges the collet means radially inwardly to engage the serrations on the collet means with the serrations on the termination member and thereby restrain axial movement of the termination member toward the position of being fully extended from the tubular housing. The invention will now be described, by way of example, with reference to the accompanying, partly diagrammatic, drawings, in which:- Figure 1 is a longitudinal sectional view of a self-adjusting cable control device in an engaged configuration; Figure 2 is a view of a portion of the device to an enlarged scale showing the device in a disengaged configuration; Figure 3 is a cross section view taken on the line III-III in Figure 1; Figure 4 is a sectional view showing the device in an initial configuration; Figure 5 is a cross section taken on the line V-V in Figure 4; and Figure 6 is a partly sectioned view of an end portion of the device with a shroud or boot in position. Referring to Figures 1 to 4, the self-adjusting cable control device is arranged to be interposed in a cable run (not shown) and comprises a connecting member in the form of a tubular housing 10 having end portions crimped into grooves on end inserts 11, 12 to hold the end inserts 11, 12 in position. A termination member in the form of a rod 13 extends through an opening in the end insert 11 which serves to locate the termination member rod . The device is connected into a cable run with first and second anchorages (not shown) on the end insert 12 and on the termination member rod 13. Clutch means releasably connecting the tubular housing 10 and the rod 13 include collet members 14 positioned around the rod 13 within a cup portion 11a of end insert 11. Each collet member 14 has a first, external, part frusto-conical surface 15 at one end adapted to engage a complementary, first, internal frusto-conical surface 16 on the end insert 11 hav ing a slightly lesser cone angle than the surfaces 15. A circumferential retaining spring 17 extends circumferentially in aligned grooves 18 in each collet member 14 resiliently to urge the collet members 14 radially inwardly into contact with the termination member 13. A helical spring 19 interposed between an abutment or shoulder 20 on the end insert 11 and a disc 21 fixed on the end of the termination member rod 13 resiliently urges the termination member rod 13 axially inwardly of the housing 10 and to the right as seen in Figure 1. Each collet member 14 is also formed at the end thereof opposite the end having surface 15, with a second, internal, part frusto-conical surface 22, complementary to a second, external, frusto-conical surface 23 on an end cap 30 secured into the cup portion 11a. The radially inner faces of the collet members 14 and a portion of the rod 13 are circumferentially grooved to form axially spaced, co-acting, 90° triangular profile, serrations 31, 32. The interengagement of the internal and external conical surfaces 22, 15 of the collet members 14 with the internal frusto-conical surface 16 of the end insert 11 and the external frusto-conical surface 23 of the end cap 30 is such as to permit the collet members 14 to maintain a co-axial disposition and disengage over the complete length of the serrations 32 on the radially inner faces. An axially movable release tube 25 extending through the end insert 11 around the termination member rod 13 has an enlarged inner end 29 engaging a shoulder 26 on the end insert 11 to retain the tube 25 against axially outward movement and is formed at a forward end with a third, external, frusto-conical surface 28. Complementary, third, internal, part frusto-conical surfaces 27 are formed on the collet member 14 with a cone angle slightly greater than the cone angle of the surface 28. As indicated in Figures 5 and 6, a plastics clip 33 is formed with an elongate circular opening having a portion 34 the periphery of which is shaped to engage against the serrations 32 and a portion 35 of greater diameter than the rod 13 but of lesser diameter than the release tube 25. Flanges 36 are provided at end portions of the clip. A convoluted shroud or boot 37 of elastic material surrounds the clip 36 and seats on the end insert 11 and the rod 13 to provide a seal against dirt, oil and other deleterious matter. In operation, to install the device into a cable run, the clip 33 is moved into a position indicated in Figure 1 in which the rod 13 passes freely through the portion 35 and in which a web portion of the clip bears against the end of the release tube 25. The clip is then urged axially toward the tubular housing 10 to move the release tube 25 axially into the tubular housing, thereby moving the enlarged inner end 29 away from the shoulder 26 and, by the inter-action of the sets of frusto-conical surfaces 28, 27 and 23, 22, moving the collet members 14 axially and radially out of engagement with the serrations 32 on the rod 13. Tension is then applied to the rod 13 and the tubular housing 10 to withdraw the rod 13 axially from the housing to an extended position and thereby compress the helical spring 19. With the rod 13 at the extended position indicated in Figure 4, the clip 33 is moved - in a direction perpendicular to the rod 13 - to engage the portion 34 with one of the serrations 32, thereby preventing retraction of the rod 13 into the tubular housing 10 by the effect of the helical spring 19. The device is then connected into the slack cable run by attachments (not shown) to the tubular housing 10 and rod 13. Having effected attachment, the clip 33 is returned to the position in which the rod 13 passes freely through the portion 35, whereupon the resilience of the helical spring 19 urges retraction of the rod 13 axially into the housing 10 and applies tension to the cable run. Upon the helical spring 19 reaching full extension commensurate with the tension in the cable r un, at an intermediate position of retraction of the rod 13 into the tubular housing 10, the resilience of the circumferential retaining spring 17 is such as to overcome the radial component of the force across the serrations 31, 32 and urge the collect members 14 radially inwardly to bring the serrations into engagement, thereby restraining axial movement between the tubular housing 10 and the rod 13. Movement of the collet members radially inwardly urges the release tube 25 axially outwardly. If, during use, the tension in the cable run falls below the force exerted by the helical spring 19 to an extent that axial movement of the rod 13 relative to the tubular housing 10 brings the frusto-conical faces 22, 23 into abutment and the radial component of the force across the serrations 31, 32 and the frusto-conical surfaces 22, 23 is sufficient to exceed the force exerted by the circumferential retaining spring 17, the rod 13 being at an intermediate position of retraction, the collet members 14 move radially outwardly out of full engagement with the rod so that the respective serrations 31, 32 ratchet to a new axial position to restore the balance of forces by adjusting the effective length of the cable run within the limits imposed by the length of the tubular housing 10. Since the convoluted shroud or boot 37 is flexible, movement of the clip 33 can be effected by applying manual pressure to the outer surface of the convoluted shroud or boot adjacent the flanges 36, so that the convoluted shroud or boot serves at all times to limit ingress of grease or dirt or other deleterious matter into the tubular housing 10. It will be appreciated that, in instances where initial tensioning of the cable run may be effected at another location in the cable run, the release tube 25 and clip 33 may be omitted from the device, which will then serve solely to maintain tension in the cable run within predetermined limits. It also will be appreciated that the serrations may be formed as a screw thread rather than axially spaced circumferential grooves. It will further be appreciated that whilst the foregoing description envisages the device being connected into a run of core cable, preferably at one end thereof, the device is readily modified to be connected into a run of conduit of a control cable. In such an arrangement the core cable extends centrally through the device and the conduit is connected into the end insert 12 and the rod 13, which are made hollow to accommodate the core cable. Alternatively, the conduit in the form of a tightly wound wire spiral, may be substituted for the rod provided strength considerations allow.

Claims: 1. A control cable adjuster device including a tubular housing (10) having at one end a first anchorage (12) connectable into a cable run and at the other end locating means (11) for a termination member (13) movably extending co-axially of the tubular housing (10) between a position fully retracted into, and a position fully extended from, the tubular housing, the termination member (13) being formed on the surface thereof with circumferential serrations (32) engageable with collet means (14) and, on the end thereof remote from the tubular housing, a second anchorage connectable into the cable run, characterised in that first resilient means (19) bias the termination member toward the position fully retracted into the tubular housing, the collet means (14) are located in the locating means and are formed on radially inner faces with serrations (31) adapted to co-act with the serrations (32) on the termination member, second resilient means (17) bias the collet means (14) radially inwardly, a first frusto-conical surface (23) in the locating means (11) at the axially inner end thereof is arranged to co-act with first, part frusto-conical, surfaces (22) on the collet means (14) such that relative axial movement of the collet means axially inwardly urges the collet means radi ally outwardly and a second frusto-conical surface (16) in the locating means at the axially outer end thereof is arranged to co-act with second, part frusto-conical, surfaces (15) on the collet means such that relative axial movement of the collet means axially outwardly urges the collet means radially inwardly to engage the serrations (31) on the collet means with the serrations (32) on the termination member and thereby restrain axial movement of the termination member toward the position of being fully extended from the tubular housing. 2. A control cable adjuster device as claimed in Claim 1, characterised in that a release tube (25) extends, co-axially of and adjacent the termination member (13), through the locating means (11) and, at the axially inner end, is formed with a third frusto-conical surface (28) arranged to co-act with third part frusto-conical surfaces (27) on the collet means (14) such that relative movement of the release tube (25) axially inwardly urges the collet means (14) radially outwardly. 3. A control cable adjuster device as claimed in Claim 2, characterised in that the cone angle of the third frusto-conical surface (28) on the release tube (25) is slightly less than the cone angle of the third part frusto-conical surfaces (27) on the collet means (14). 4. A control cable adjuster device as claimed in Claim 2 or Claim 3, characterised in that the release tube (25) is formed at the axially inner end with an enlarged head (29) arranged to be seatable in a counter-bore (26) in the locating means (11). 5. A control cable adjuster device as claimed in Claim 2, Claim 3 or Claim 4, characterised in that a clip (33) is provided on a portion of the termination member (13) external to the tubular housing (10) and is movable between an engaged position, at which the clip (33) is engaged with at least one of the serrations (32) on the termination member, and a disengaged position, at which the clip is disengaged from the serrations (32). 6. A control cable adjuster device as claimed in Claim 5, characterised in that the clip (33) is formed as an elongate circular disc having an elongate circular aperture one portion (34) of which is narrower than the other portion (35) to engage the serrations (32) and the circular ends of the disc are formed with flanges (36). 7. A control cable adjuster device as claimed in any preceding claim, characterised in that the first resilient means (19) include a helical spring extending between a seating (20) on the locating means (11) and a collar (21) attached to the termination member at an end portion located within the tubular housing (10). 8. A control cable adjuster device as claimed in any preceding claim, characterised in that the second resilient means (17) include a circumferential spring positioned in circumferentially extending grooves (18) in radially outer faces of the collet means (14). 9. A control cable adjuster device as claimed in any preceding claim, characterised in that the serrations (31,32) are formed as axially spaced circumferential grooves of 90° triangular profile. 10. A control cable adjuster device as claimed in any preceding claim, characterised in that a flexible convoluted shroud or boot (37) is provided as a seal between the tubular housing (10) and the termination member (11). 11. A control cable adjuster device as claimed in any preceding claim, characterised in that the cone angle of the second frusto-conical surface (16) in the locating means (11) is slightly lesser than the cone angle of the second, part frusto-conical surfaces (15) on the collet means (14).

Inventors: PICKELL, JOHN MIDDLETON
Applicants: ACCO BABCOCK INC.
Application year: 1987
Main classification: F16C1
IPC codes: F16C1, B60K23, F16D23, B62L3