GB2246389A - Strap adjuster - Google Patents

Abstract

A strap adjuster comprises an adjustor body 10 having a belt guide surface 36, and a pivotally mounted clamping member 38 with an eccentric clamping surface 42. The clearance between the guide surface 36 and the clamping surface 42 reduces with angular movement of the clamping member. Movement of a strap 50 in one direction causes angular movement of the clamping member 38 in a direction to reduce this clearance so as to wedge the strap between the clamping surface 42 and the guide surface 36 thereby inhibiting further movement of the strap 50 in said one direction. An additional guide member 48 is mounted on the adjuster body 10 so as to hold the strap 50 out of engagement with the clamping surface 42 when the clamping member 38 is displaced from its clamping position by more than a predetermined angle, as shown in Figure 5. <IMAGE>

Description

STRAP ADJUSTER This invention relates to a strap adjuster of the type comprising an adjuster body having a belt guide surface and a clamping member pivotally mounted on the adjuster body and having an eccentric clamping surface confronting the belt guide member to define a belt path of thickness which varies with angular movement of the clamping member, whereby movement of a strap in one direction along said strap path causes angular movement of the clamping member in a direction to reduce the thickness of the belt path so as to wedge the strap between the clamping surface and the guide surface thereby inhibiting further movement of the strap in said one direction.

When it is desired to adjust the strap, the clamping member is manually displaced in the opposite direction so as to increase the thickness of the strap path. A large angular movement occurs during reengagement of the clamping member, with the result that an excessive length of strap is paid out.. The present invention aims to provide an adjuster of the type described above which is not subject to this disadvantage.

According to the invention, in a strap adjuster of the type described above, an additional guide member is mounted on the adjuster body so as to hold the strap out of engagement with the clamping surface when the clamping member is displaced from its clamping position by more than a predetermined angle.

In addition to overcoming the disadvantage mentioned above, an adjuster in accordance with the invention has the advantage of reducing friction as the strap paid out through the adjuster. In addition, if the clamping surface is serrated, abrasion of the strap is reduced.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a longitudinal cross-sectional view of a known strap adjuster with its clamping member in the clamping position; Figure 2 is a longitudinal cross-sectional view of the strap adjuster shown in Figure 1, but with the clamping member in its release position; Figure 3 is a cross-sectional view, similar to Figure 1, of a strap adjuster in accordance with the invention; Figure 4 is a plan view of the strap adjuster shown in Figure 3; and Figure 5 is a cross-sectional view, similar to Figure 2, of the strap adjuster shown in Figure 3.

Referring to Figure 1, a known strap adjuster has a U-shaped body with a base portion 10 and two side flanges of which only the side flange 12 is visible in the drawings. A guide bar 16 extends between the side flanges and a clamping member 18 is mounted on a pivot pin 20 which also extends between the two flanges. The clamping member 18 has a serrated arcuate clamping surface 22 which is eccentric with respect to the pivot pin 20 so that angular movement of clamping member 18 about the pivot pin 20 in the clockwise direction (as viewed in Figure 1) causes the distance between the clamping surface and the guide bar 16 to be reduced. A spring (not shown) biasses the clamping member 18 in the clockwise direction.

A strap 24 passes between the guide bar 16 and the clamping surface 22. When a load is applied to the left hand end of the strap 24, any slipping movement relative to the guide bar 16 tends to rotate the clamping member 18 in the clockwise direction, thus increasing the clamping force exerted by the clamping surface 22.

The clamping member 18 has an integral lever 28.

When it is desired to move the strap 24 relative to the adjuster, the lever 28 is used to pivot the clamping member 18 in the counter-clockwise direction so that the strap 24 is free to move between the guide bar 16 and the clamping surface 22. If the strap is then displaced to the right, as viewed in the drawings, the clamping member 18 tends to pivot further in the counter-clockwise direction at least as far as the position shown in Figure 2. When the strap has been adjusted to its required position and the lever 28 is released, a significant length of strap slips over the guide bar 16 as the clamping member 18 pivots back to the position shown in Figure 1.

Referring to Figures 3 and 4, a strap adjuster in accordance with the invention has a U-shaped body with a base portion 30 and two side flanges 32 and 34. A guide bar 36 extends between the flanges 32 and 34. A clamping member 38 is pivotally mounted on a pivot pin 40 extending between the side flanges 32 and 34 and has an arcuate eccentric clamping surface 42 which co-operates with the guide bar 36 in a similar manner to the clamping surface 22 of Figures 1 and 2. The clamping member 38 has an integral lever 44 whereby it may be displaced manually. A spring 46 engages with the side flange 34 and biasses the clamping member 38 in the clockwise direction as vi.ewed in Figure 3.

In accordance with the invention, a guide pin 48 extends between the side flanges 32 and 34 at a location in alignment with the edge of the guide bar 36 nearest to the clamping member 38. A strap 50 extends round the guide bar 36 and then round the guide pin 48. In normal use, a load on the strap 50 is applied to the end 52 thereof. The spring 46 biasses the clamping surface 42 into engagement with the strap 50 and any tendency of the strap 50 to slip causes the clamping surface to move into firmer engagement therewith, in a similar manner to that described with reference to Figure 1.

When the strap 50 is to be adjusted, the lever 44 is used to displace the clamping member 38 in the counterclockwise direction. After even a small displacement, and well before the clamping member 38 reaches the position illustrated in Figure 5, the clamping surface 42 is out of contact with the strap 50 which can therefore freely slide round the guide bar 36 and the guide pin 48. When -the lever 44 is released, the spring 46 urges the clamping member 38 back into engagement with the strap 50 and only a small length of strap is paid out as the clamping member 38 moves to its fully clamped position.

Since the pin 48 holds the strap 50 clear of the serrated clamping surface 42 during adjustment, the risk of abrasion damage to the strap 50 is reduced. Moreover, the friction resisting adjustment when the lever 38 is in the position illustrated in Figure 5 is significantly lower than the friction when the lever 18 is in the position illustrated in Figure 2. This friction can be still further reduced by journaling a roller on the guide pin 48.

Claims (3)

1. A strap adjuster comprising an adjuster body having a belt guide surface and a clamping member pivotally mounted on the adjuster body and having an eccentric clamping surface confronting the belt guide member to define a belt path of thickness which varies with angular movement of the clamping member, whereby movement of a strap in one direction along said strap path causes angular movement of the clamping member in a direction to reduce the thickness of the belt path so as to wedge the strap between the clamping surface and the guide surface thereby inhibiting further movement of the strap in said one direction, an additional guide member being mounted on the adjuster body so as to hold the strap out of engagement with the clamping surface when the clamping member is displaced from its clamping position by more than a predetermined angle.

2. A strap adjuster according to claim 1, wherein the adjuster body has two mutually parallel side walls betweer.

which the clamping member is pivotally mounted, the belt guide member and the additional guide member being secured to the side walls so as to extend therebetween.

3. A strap adjuster substantially as hereinbefore described with reference to Figures 3 to 5 of the accompanying drawings.

3. A strap adjuster substantially as hereinbefore described with reference to Figures 3 to 5 of the accompanying drawings.

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS 1. A strap adjuster comprising an adjuster body having a belt guide surface and a clamping member pivotally mounted on the adjuster body and having an eccentric clamping surface confronting the belt guide member to define a belt path of thickness which varies with angular movement of the clamping member, whereby movement of a strap in one direction along said strap path causes angular movement of the clamping member in a direction to reduce the thickness of the belt path so as to wedge the strap between the clamping surface and the guide surface thereby inhibiting further movement of the strap in said one direction, an additional guide member being mounted on the adjuster body so as to engage with the strap at a location spaced from the belt guide member in said one direction along said belt path thereby to hold the strap out of engagement with the clamping surface when the clamping member is displaced from its clamping position by more than a predetermined angle.

2. A strap adjuster according to claim 1, wherein the adjuster body has two mutually parallel side walls between which the clamping member is pivotally mounted, the belt guide member and the additional guide member being secured to the side walls so as to extend therebetween.