GB1576535A

GB1576535A - Retaining device for detachably securing the tip of mechanical digger prong

Info

Publication number: GB1576535A
Application number: GB3652877A
Authority: GB
Original assignee: O&K Orenstein and Koppel GmbH
Current assignee: CNH Industrial Baumaschinen GmbH
Priority date: 1976-09-04
Filing date: 1977-09-01
Publication date: 1980-10-08
Also published as: JPS5927806B2; IT1079829B; JPS5332901A; ATA555877A; AU2836977A; DE2639989C2; BR7705873A; AT352640B; FR2363669B1; AU507527B2; FR2363669A1; DE2639989A1; BE858281A; CA1069961A

Description

(54) RETAINING DEVICE FOR DETACHABLY SECURING THE TIP OF A MECHANICAL DIGGER PRONG (71) We, O. & K. ORENSTEIN & BR< KOPPEL AKTIENGESELLSCHAFT, a German Company, of 1000 Berlin 20, Brunsbiitteler Damm 144--208, Germany, 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 retaining device for detachably securing the tip of a mechanical digger prong to a holder which is solidly connected to a digging implement, for example to the digging edge of a bucket.

In known conventional arrangements, a peg on the holder extends into a rearwardlyextending sleeve on the prong tip, and the prong tip is detachably secured to the peg by means of a connecting element which is arranged in an opening extending parallel to the cutting edge of the tip. The connecting element consists of two shaped metal parts and of a rubber element under compression and disposed between these two parts, and, in the fitted position, the connecting element bears, on the one hand, on those faces of the prong-tip openings that are presented to the cutting edge and, on the other hand, on the faces, remote from the cutting edge, of a recess formed in the peg.

In a known prong-retaining device of this kind (French Patent Specification 2,264,140), the opening in the peg is itself of substantially oval cross-section. The faces of the two shaped metal parts that are presented to the rubber element are uniformly flat, so that the rubber element can be compressed as much as required. Thus, during dynamic loading as a result of digging operations, the permissible loading limit of the rubber element is soon reached and, since the rubber cannot recover, it therefore loses its spring force.

In another known prong-retaining device (German Patent Specification AS 1,960,411), it is the holder that is provided with a sleeve into which the tip of the prong is inserted.

In this arrangement, stops on the side parts of the connecting element extend across the resilient intermediate layer of the element and, between them, form a gap, the width of which is less than the thickness of the resilient intermediate layer. This arrangement is intended to prevent excessive continuous loading of the resilient intermediate layer as a result of the dynamic loads occurring during digging operations. On the other hand however a strong spring force is required in the resilient intermediate layer so as to hold the connecting element in position.In contrast to the load conditions occurring during longterm operation when the long-term loadability of the resilient intermediate layer has to be taken into account, the resilient intermediate layer could be heavily compressed without harmful consequences when forcing the connecting element in and out during the necessary changing of the tip of the prong, since in this case only static loading of the resilient intermediate layer is involved. However, this cannot be achieved with the known retaining device since the width of the gap defined by the side parts of the connecting element does not permit variable compression. The possible spring excursion of the resilient intermediate layer is therefore only partially utilized when the connecting element is forced out.If, in the known arrangement, the gap were increased so allowing greater compression of the resilient intermediate layer to occur, the rubber, as in the other above-mentioned prong-retaining device, would soon reach the limit of its permitted loadability because of the dynamic loading during a digging operation and it would then not perform its function as a spring element.

Furthermore, in the known arrangement, the resilient layer would be compressed only on one side when forcing out the connecting element, since the latter is forced out on each side only by way of a cam. Because of this arrangement and on account of the incompletely utilized spring excursion during the forcing out of the connecting element, only part of the spring force of the resilient intermediate layer is utilized in the known prong-retaining device. The resistance of the connecting element to lateral forces is thus relatively low, and the tip of the prong cannot be secured in the best possible way to the holder by means of the connecting element.

The present invention provides a retaining arrangement for detachably securing the tip of a mechanical digger prong to a holder, in which the prong tip member or the holder member has a sleeve into which a peg on the other member extends, and in which a connecting element is arranged in a bore formed by substantially-aligned openings in the peg and the side walls of the sleeve, the connecting element consisting of two shaped parts and a resilient element under compression and disposed between those two parts, one of the said parts being U-shaped and straddling the other shaped part, the back of the U-shaped part resting against the wall of the opening in the peg, and the limbs of the U-shaped part being . disposed in the openings in the sleeve and constituting stops co-operable with the walls of the sleeve openings to prevent the resilient element from being subjected to a load exceeding the fatigue limit, and the said other shaped part of the connecting element being provided with lugs located in recesses in the wall of the bore, the height of the lugs being such that when the connecting element is driven out of the said bore to release the prong tip from the holder, the resilient element is compressed to: a greater degree than during a digging operation.

Preferably, the back of the U-shaped part and the wall of the opening in the peg are provided with co-operating inclined faces.

An embodiment of the invention will now be described, by way of example, with refer pence to the attached drawings, in which: Fig. 1 is a longitudinal section through the prong of a mechanical digger, and Fig. 2 is a cross-section along the line X XofFig. 1.

The tip 20 of the prong of a mechanical digger consists of a cutting edge 21 and a sleeve 22 whereby the tip 20 is pushed over a peg 23 on a holder. Within the forward third of its length the peg 23 has an opening 24 which extends through the longitudinal centre line parallel to the cutting edge 21 and which corresponds to openings 25 in the sleeve 22, so that a connecting element 26 can be accommodated therein to detachably secure the prong tip 20 to the holder. The connecting element 26 is a one-piece element and consists of a U-shaped metal part 27 interconnected by a rubber element 28 to a shaped metal part 29. The U-shaped part 27 straddles the rubber element and is opensided between its limbs 27c.

On its surface facing the base of the peg 23, the shaped metal part 29 has lugs 30 which are more steeply sloped on their sides 30c facing the sleeve 22 than on their sides 30b facing the peg 23. The peg 23 is provided with recesses providing complementary inclined faces 31 which co-operate with the inclined faces 30b of the lugs 30. Formed on the U-shaped. metal part 27 are inclined faces 27a which co-operate with complementary inclined faces 23a on the peg 23. The opening 24 in the peg 23 is provided with a recess 32 in that of its faces presented to the cutting edge 21, so as to delimit the inclined faces 23a in a clear manner. The limbs 27c of the Ushaped metal part extend towards the open end of the sleeve 22.

During earth-digging operations, the rubber element 28 of the connecting element 26 is prevented from being subjected to a load exceeding the fatigue limit of the rubber element by the limbs 27c of the U-shaped metal part 27 acting as stops co-operable with the faces 33 of the sleeve 22. To this end, it is arranged that the width of the gap between the end face of the limbs 27c and the faces 33 of the sleeve 22 is smaller than the spring excursion of the rubber element 28 that is permissible for maintaining the fatigue strength of the rubber element. As a result the rubber element remains durable and exhibits no fatigue when the tip of the prong is dynamically loaded over a lengthy period during earth-digging operations.

The procedure for driving the connecting element 26 out of the opening 24, 25, to release the prong tip 20 from the holder, is as follows. The operator strikes the end face 27b of a limb 27c of the shaped metal part 27 with a heavy hammer, and the shaped metal part 29 is driven by way of the limb.

Increasing compression of the rubber element 28 takes place, on the one hand, by way of the inclined face 27a of the U-shaped metal part 27 and the co-operating inclined face 23a of the peg 23 and, on the other hand, by way of the lug faces 30b and 30c of the shaped metal part 29 and the co-operating inclined face 31 on the peg 23 and the face 33 of the sleeve 22. When the connecting element 26 is driven out a further distance, the rubber element 28 is more heavily compressed than by the load occurring during earth-digging operations and may, indeed, be loaded up to its elastic limit although it should not, of course, be so heavily loaded that it shears.

The lugs 30 and the inclined surfaces 30b, 30c, 27a of the connecting element and the complementary surfaces 31, 23a of the peg and of the prong tip are so arranged that, when the connecting element is driven out, the rubber element is substantially uniformly compressed over its entire length.

Consequently, the spring force of the rubber element 28 is utilized in the best possible way for immobilizing the connecting element when in the fitted position and the prong tip 20 is thus provided with a secure hold on the prong holder even under the heaviest loads.

Claims

WHAT WE CLAIM IS:

1. A retaining arrangement for detachably securing the tip of a mechanical digger prong to a holder, in which the prong tip member or the holder member has a sleeve into which a peg on the other member extends, and in which a connecting element is arranged in a bore formed by substantially-aligned openings in the peg and the side walls of the sleeve, the connecting element consisting of two shaped parts and a resilient element under compression and disposed between these two parts, one of the said parts being U-shaped and straddling the other shaped part, the back of the U-shaped part resting against the wall of the opening in the peg, and the limbs of the U-shaped part being disposed in the openings in the sleeve and constituting stops co-operable with the walls of the sleeve openings to prevent the resilient element from being subjected to a load exceeding the fatigue limit and the said other shaped part of the connecting element being provided with lugs located in recesses in the wall of the bore, the height of the lugs being such that when the connecting element is driven out of the said bore to release the prong tip from the holder, the resilient element is compressed to a greater degree than during a digging operation.

2. A retaining arrangement according to claim 1, in which the width of the gap between the end faces of the limbs and the walls of the sleeve openings is smaller than the spring excursion of the resilient element that is permissible for maintaining the fatigue strength of the resilient element.

3. A retaining arrangement according to claim 1 or claim 2, in which the back of the U-shaped part of the wall of the opening in the peg are provided with co-operating inclined faces.

4. A retaining arrangement according to claim 3, in which the wall of the opening in the peg is provided with a recess to delimit the inclined faces therein.

5. A retaining arrangement according to any one of the preceding claims, in which the U-shaped member is open-sided between the limbs.

6. A retaining arrangement according to any one of the preceding claims, in which the connecting element is a one piece element.

7. A retaining arrangement according to any one of the preceding claims, in which the limbs of the U-shaped member extend towards the open end of the sleeve.

8. A retaining arrangement according to any one of the preceding claims, in which the connecting element and the bore in which it is located are so shaped that, when the connecting element is driven out of the bore to release the prong tip from the holder, the resilient element is substantially uniformly compressed over its entire length.

9. A retaining arrangement for detachably securing the tip of a mechanical digger prong to a holder, substantially as described herein with reference to, and as illustrated by, the accompanying drawings.