GB2275296A

GB2275296A - A clampable carriage sliding on a track.

Info

Publication number: GB2275296A
Application number: GB9303516A
Authority: GB
Inventors: Victor Horace Groom
Original assignee: N M I SAFETY SYSTEMS Ltd; NMI IND SERVICES Ltd; NMI Safety Systems Ltd
Current assignee: N M I SAFETY SYSTEMS Ltd; NMI IND SERVICES Ltd; NMI Safety Systems Ltd
Priority date: 1993-02-22
Filing date: 1993-02-22
Publication date: 1994-08-24
Anticipated expiration: 2013-02-22
Also published as: GB2275296B; GB9303516D0

Abstract

A carriage 1 which is slidably mounted on a track 2, which track comprises an elongate upwardly open channel formed with at least one longitudinally extending lip 6, 7 has guide means 12 engageable with the track and a screw clamp 12 engageable with the lip of the track. The clamp (see Fig 8) comprises a headed member 42 engaging under the tips of the track. The track also has widened nominally circular locations 8 to allow for introduction and removal of the heads 42. The head is attached to a threaded shaft 37 which extends through the carriage to an internally threaded cap 36, rotation of which causes the head to clamp to the underside of the lips. Item 11 Fig. 1 in a retractable stud bolt (Figs. 5, 6, not shown) which fits the circular openings to lock the carriage in a chosen position on the track. <IMAGE>

Description

"A CARRIAGE" The present invention relates to an apparatus for locking a carriage to a track and more particularly to a carriage screw clamp for securing a moveable carriage to a track.

Tracks are often provided in the floors of ambulances and other vehicles. When items are loaded into the vehicles the items may be clamped or locked on one or more slidable carriages mounted on the tracks. Each carriage can be slid along the track and a spring bassed plunger released to lock the carriage in a desired position along the track. However, whilst the spring biased plunger may locate the carriage in the desired position, the carriage is not securely locked into position and, if the spring biassed plunger is released, the carriage is once again free to move. The carriage, even when retained by the plunger, tends to rattle due to the necessary play between the carriage and the track.

It is therefore an object of the present invention to provide a carriage screw clamp which securely locks the carriage into position on the track and which prevents any minor movement of the carriage with respect to the track.

Accordingly, in one aspect the present invention provides a carriage adapted to be slidably mounted on a track comprising an elongate upwardly open channel formed with at least one longitudinally extending lip, the carriage having a guide means which is engageable with the track for guiding the carriage along the track and a carriage screw clamp comprising engaging means engageable with the lip of the track and means for urging the engaging means into contact with the underside surface of the lip of the track to secure the carriage to the track.

In order that the present invention may be more readily understood, an embodiment thereof will be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side view of a carriage including a carriage screw clamp according to one embodiment of the present invention; Figure 2 is a plan view of a track suitable fcr use with one embodiment of the present invention; Figure 3 is a cross section through the track of Figure 2 along the line III - III; Figure 4 is a cross section through a guide element for use with one embodiment of the present invention; Figure 5 is a cross section through a spring biassed plunger in a first condition; Figure 6 is a cross section through the spring biassed plunger of Figure 5 in a second condition; Figure 7 is a perspective view of a collar forming part of the plunger of Figures 5 and 6; and Figure 8 is an enlarged cross section through a carriage screw clamp of the carriage of Figure 1 taken along the line VIII - VIII in Figure 1 and showing the carriage mounted on the track of Figure 2.

Referring now to Figure 1, a carriage 1 is shown which is mountable on a track 2 as shown in Figures 2 and 3 which is embedded in the floor of a vehicle such as an ambulance.

The track 2, as seen in Figures 2 and 3, comprises a single elongate piece of extruded aluminium formed as an upwardly open channel of generally C-shaped cross-section.

The channel is defined by a base plate 3 and two upstanding elongate side walls 4, 5 which terminate at two inwardly facing and opposed lips 6, 7. The end of the lips 6, 7 have a thickness T. The lips 6, 7 are provided with a number of arcuate cut-away segments 8 at regular intervals along the length of the track 2. Each cut-away segment 8 on each lip 6, 7 is directly opposite a corresponding cutaway segment 8 on the opposite lip 7, 6. Each pair of opposite, arcuate cut-away segments 8 define a nominal circle. Between each cut-away segment 8 on each lip 6, 7 is formed a linear edge portion 9 which is parallel to the longitudinal axis of the track 2 and which links the ends of the arcuate cut-away segments 8. The linear edge portions 9 of each lip 6, 7 are co-aligned, the linear portions of the two edges being parallel and spaced apart by a predetermined distance G. The underside of the linear part of each lip defines an engaging surface. The length of the linear edge portions 9 is approximately half the length of the diameter of the nominal circle defined by the arcuate cut-away segments 8.

The carriage 1 comprises a single elongate element having a width which is slightly narrower than the width of the track 2. The particular carriage 1 shown in Figure 1 carries an anchorage point 10 at both ends, a spring biassed plunger 11 midway along the length of the carriage 1 and two carriage screw clamps 12 each located substantially midway between the spring biassed plunger 11 and a respective anchorage point 10.

Each anchorage point 10 comprises a suitable receptacle which is located on the top surface of the carriage 1 and which is adapted to receive a portion of any article which is to be connected to the carriage 1. The anchorage point 10 has a stud 13 which extends from the receptacle through a through-hole 14 in the carriage 1.

The stud 13 protrudes from the underside of the carriage 1.

The underside of the carriage 1 adjacent the protruding stud 13 is provided with a longitudinally extending slot or recess 15 which is formed parallel to the longitudinal axis of the track 2. A guide element 16, shown in Figure 4, having a vertical threaded bore comprises a rectilinear spacer block 17 and a head 18. The anchor point 10 is securely fastened to the carriage 1 by tightening the stud 13 and the guide element 16 together, with the stud 13 received in the threaded bore.

The spacer block 17 is partially received within the slot 15 and is of substantially the same profile as the slot 15. This prevents the stud receiving element 16 from rotating when the stud 13 is being threaded into the guide element 16. The width of the slot 15 and hence the width of the spacer block 17 received within the slbt 15 is less than the gap G between the linear portions 9. The head 18 comprises a circular plate which is integrally formed with the spacer block 17. Two arcuate segments 19, 20 of the head 18 project from the spacer block 17 and are sloped on their arcuate surfaces adjacent the spacer block 17. The spacer block 17 spaces the head 18 from the underside surface of the carriage 1 by a distance which is slightly larger than the thickness T of the ends of the track lips 6, 7. The diameter of the circular head 18 is slightly smaller than the diameter of the nominal circle defined by two opposed arcuate cut-away segments 8. The profile of the stud receiving element 16 along its longitudinal axis corresponds to the internal cross section of the track 2.

Thus, the stud receiving element 16 when carried upon the carriage 1 can slide along the track 2.

The spring biassed plunger 11 is shown in detail in Figure 5 and 6 and comprises an assembly consisting of five main component parts: a plunger 21; a collar 22; a compression spring 23; a pin 24; and a housing cap 25.

The collar 22, shown in detail in Figure 7, is a hollow cylinder and is formed at one end with an annular outwardly facing extending flange 26. The resulting cylinder has a single inner diameter, a main body outer diameter and a flange portion outer diameter which is greater than the main body outer diameter. The annular flange 26 is provided with two diametrically opposed cutouts 27, 28 formed on the end surface 29 of the flange portion.

The compression spring 23 encircles the main body outer diameter of the collar 22 and is prevented from moving off the flanged end of the collar 22 by the annular flange 26. The plunger 21 consists of a solid cylinder dimensioned to be slidably received within the collar 22.

The end of the plunger 21 adjacent the flanged end of the collar 22 is provided with a through-hole 30 which passes through and is perpendicular to the cylindrical axis of the plunger 21. The diameter of the plunger 21 is slightly smaller than the diameter of the nominal circle defined by each pair of opposite cut-away segments 8 in the track 2.

The housing cap 25 is a hollow cylinder which is formed at one end with an annular inwardly facing flange 31. The housing cap 25 therefore has a single outer diameter, a main body inner diameter and a flange portion inner diameter which is smaller than the main body inner diameter. The main body inner diameter is slightly larger than the flanged portion outer diameter of the collar 22 and the flanged portion inner diameter is slightly larger than the main body outer diameter of the collar 22. Thus, the collar 22 is slidably receivable within the housing cap 25 such that the compression spring 23 is sandwiched between the flange 26 of the collar 22 and the flange 31 of the housing cap 25. The outer surface of the housing cap 25 is knurled to provide a good hand gripping surface.

The housing cap 25 is formed with two diametrically opposed through-holes 32, 33 near the non-flanged end of the housing cap 25. A pin 24 is placed through the first through-hole 32 and the housing cap 25, through the through-hole 30 and the plunger 21 and through the second through-hole 33 in the housing cap 25 to secure the housing cap 25 to the plunger 21. The pin 24 can rest in either of two conditions. The first condition is when the pin 24 rests on the end surface 29 of the flanged portion of the collar 22. The second condition occurs when the pin 24 is aligned with the diametrically opposed cut-outs 27, 28 on the collar 22. In this condition, the pin 24 is received by the cut-outs 27, 28 and is biased into this position by the compression spring 23. When in the first condition, the plunger 21 does not protrude from the collar 22.

However, when in the second condition, the plunger 21 does protrude from the collar 22.

With the plunger 21, the collar 22, the compression spring 23 and the pin 24 received within the housing cap 25, the non-flanged end of the housing cap 25 is closed with an end cap 34 which is placed in force fit engagement with the main body inner diameter of the housing cap 25.

The assembled unit comprises the spring biased plunger 11.

The carriage 1 is provided with a fixing hole 35 to receive the spring biassed plunger 11. The fixing hole 35 is dimensioned to receive the non-flanged end of the collar 22 in force fit engagement, the non-flanged end of the collar 22 being flush with the underside surface of the carriage 1 when fitted. Thus, when the carriage 1 is mounted on the track 2 and the pin 24 rests upon the end surface 29 of the flanged portion of the collar 22, the plunger 21 does not enter the track 2, whereas, wh the pin 24 rests in the cut-outs 27, 28 on the collar 22, the plunger 21 protrudes from the underside surface of the carriage 1 and, if the plunger 21 is directly opposite a pair of cut-away segments 8, then the plunger 21 will be received between the cut-away segments 8 in the track 2 which prevents the plunger 21 from moving along the track 22.

As shown in Figure 8, the screw clamp 12 comprises four main components which are: a locking cap 36; a clamp bolt 37; an end stop plate 38; and a screw clamp end cap 39.

The locking cap 36 is similar to the housing cap 25 and is a cylinder having an annular inwardly extending flange 40 at one end. The inner diameter of the flanged portion comprises a threaded bore. To provide a good hand gripping surface, the outer surface of the locking cap 36 is knurled. The locking cap 36 is located on the top surface of the carriage 1.

The clamp bolt 37 comprises a threaded shaft 41 for co-operating with the threaded bore of the locking cap 36 and a bolt head 42 formed as a disc shaped plate having two convex surfaces. The bolt head 42 is located on the bottom or underside surface of the carriage 1. The diameter of the bolt head 42 is slightly smaller than the diameter of the nominal circle defined by each pair of cut-away segments 8. The end stop plate 38 is secured to the tip of the clamp bolt 37 by fastening means and has a diameter which is slightly less than the inner main body diameter of the locking cap 36. When fitted, the end stop plate 38 prevents the clamp bolt 37 from being withdrawn from the locking cap 36 by abutting the locking cap flange 40.

Thus, when the clamp bolt 37 is passed upwardly through a clamp bolt bore 43 in the carriage 1 and the locking cap 36 is threaded onto the clamp bolt 37, the carriage 1 is sandwiched between the bolt head 42 and the locking cap 36.

The screw clamp end cap 39 is placed in force fit engagement in the non-flanged end of the locking cap 36 to close the locking cap 36.

A key-way slot 44 is formed on the threaded shaft 41 near the bolt head 42 and runs parallel to the longitudinal axis of the clamp bolt 37. A threaded bore 45 is provided in the carriage 1 perpendicular to the axis of the clamp bolt bore 43 such that a locking screw 46 such as a grub screw or the like received in the threaded bore 45 projects into the key-way slot 44 on the clamp bolt 37 preventing rotation of the clamp bolt 37 with respect to the carriage 1. Thus, rotation of the locking cap 36 in one direction will cause the bolt head 42 to move towards the carriage 1 and rotation in the other direction will cause the bolt head 42 to move away from the carriage 1.

In operation, the carriage 1 of Figure 1 is lowered onto the track 2 so that the circular plates of the stud receiving element heads 18 and the bolt heads 42 each register with a corresponding pair of cut-away segments 8.

The clamp bolts 37 of both the screw clamps 12 are fully unclamped and the spring biassed plunger 11 is in the first condition with the plunger 21 being flush with the underside surface of the carriage 1. In this configuration, the carriage 1 can be freely slid along the length of the track 2. When the carriage has been slid into a desired position along the track 2, the spring biassed plunger 11 can be placed in the second condition by rotating the housing cap 25 until the pin 24 aligns with the cut outs 27, 28. If the plunger 21 is directly opposite a pair of cut-away segments 8, then the plunger with locate between the cut-away segments 8 and prevent further longitudinal movement of the carriage 1. However, if the plunger 21 is not directly opposite a pair of cutaway segments 8, then the carriage will need to be moved a small distance so that the plunger 21 can locate between a pair of cut-away segments 8. A positive click is heard when the plunger 21 is correctly aligned with a pair of cut-away segments 8. With the plunger 21 located in the track 2, the carriage 1 may not now be moved from the track 2 as the head 18 and the bolt heads 42 are each located underneath a pair of linear portions 9 and may not be moved along the track 2 as the plunger 21 abuts the cut-away segments 8 when such movement is attempted. However, a small amount of movement is still possible due to the clearance between the heads 18, the bolt heads 42 and the track lips 6, 7, and, if for any reason the plunger 21 is released into the first condition, for example, during transit, then the carriage 1 would once more be free to move along the track 2. Thus, to securely clamp the carriage 1 to the track 2, both locking caps 35 are rotated to bring the bolt heads 42 towards the locking cap 36 thereby urging the bolt heads 42 into contact with the underside surface of the lip of the track 2 and both sandwiching and securely clamping the carriage 1 and the track 2 together. With both locking caps 36 fully tightened, no movement of the carriage with respect to the track 2 is possible and the condition of the plunger 21 is irrelevant to the security of the clamping action.

The anchor points 10 act as a point of attachment for any article which is to be secured to the carriage.

The anchor points 10 can be used to secure any number of articles where it is important to have a degree of adjustment such as to secure an adjustable seat belt anchorage point positioner, to secure guide lines to the carriage and the like. As such, the anchor point 10 may be a declip, a cleat, or any manner of connector.

The embodiment shown in Figure 1 illustrates a carriage carrying two anchor points 10, a single spring bias plunger 11 and two carriage screw clamps 12. It is envisaged that a carriage carrying a single spring bias plunger 11, a single anchor point 10 and a single carriage screw clamp 12 would be sufficient to securely clamp the carriage to the track and to provide efficient sliding characteristics. It has also been envisaged that the carriage screw clamp 12 could be combined with the anchor point 10.

Additionally, other cross sectional profiles of the track and the bolt head 42 have been considered.

Claims

CLAIMS:

1. A carriage adapted to be slidably mounted on a track comprising an elongate upwardly open channel formed with at least one longitudinally extending lip, the carriage having a guide means which is engageable with the track for guiding the carriage along the track and a carriage screw clamp comprising engaging means engageable with the lip of the track and means for urging the engaging means into contact with the underside surface of the lip of the track to secure the carriage to the track.

2. A carriage according to Claim 1, wherein, the engaging means comprises an enlarged head formed on a threaded shaft, which shaft extends through the carriage.

3. A carriage according to Claim 2, wherein the enlarged head comprises a disc shaped plate.

4. A carriage according to Claim 2 or 3, wherein the urging means comprises a threaded cap which receives the threaded shaft of the engaging means.

5. A carriage according to Claim 4, wherein the threaded cap has a knurled outside surface.

6. A carriage according to any one of Claims 2 to 5, wherein the threaded shaft has an end stop plate formed at its tip inside the securing means to prevent the securing means from becoming separated from the threaded shaft.

7. A carriage according to any preceding claim, wherein the guide means is engageable with the underside surface of the lip of the track.

8. A carriage according to any preceding claim, wherein a plunger is provided on the carriage for locating the carriage at a predetermined position along the track.

9. A carriage according to any preceding claim in combination with a track, the track comprising an elongate channel formed with at least one longitudinally extending lip.

10. A carriage in combination with a track according to Claim 9, wherein the track comprises a single piece of elongate extruded aluminium having a generally C-shaped cross section and including two opposite inwardly oriented lips.

11. A carriage in combination with a track according to Claim 10, wherein the lips of the track are formed with apertures for receiving the guide means and the engaging means.

12. A carriage in combination with a track according to Claim 11, wherein the apertures are generally circular in shape.

13. A carriage according to any one of Claims 9 to 12 wherein the carriage is provided with a plunger which locates the carriage at a predetermined position along the track on which the carriage is slidably mounted by engaging an aperture formed in the track.

14. A carriage according to Claim 13, wherein the plunger is spring biassed.

15. A carriage according to Claim 13 or 14, wherein the plunger and the aperture are of circular cross section.

16. A carriage according to any one of Claims 9 to 15, wherein the cross section of the engaging means corresponds to the cross section of the channel of the track on which the carriage is slidably mountable.

17. A carriage according to any one of Claims 9 to 16, wherein the guide means comprises an enlarged head attached to the carriage, the cross section of the enlarged head being substantially equivalent to the cross section of the channel of the a track on which the carriage is slidably mountable.

18. A carriage substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

19. A carriage in combination with the track substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

20. Any novel feature or combination of features disclosed herein.