GB2269613A - Digging apparatus - Google Patents

Abstract

A digging apparatus such as a trencher comprises a ground running vehicle towing behind it a driven digging wheel 6 disposed in a vertical plane. The digging wheel 6 is formed by a disc 26 which rotates on an axle arrangement 22 supported between a pair of support brakets of which one is shown at 20, the support brackets being connected to the vehicle. At its periphery 23 the digging wheel mounts a plurality of digging projections or cutter tips 24. A gear wheel 50 secured to a side of the disc 26 has gear teeth 52 on its outer periphery. These teeth mesh with those of a pinion 58 mounted on a driving shaft 60 driven by a motor clamped to the flange 20. Thus the motor drives the digging wheel. A cover 74 encloses the lower part of the gear wheel 50. <IMAGE>

Description

Digging Apparatus This invention concerns digging apparatus to dig material from the ground, for example in digging trenches or in mining or quarrying of the material.

The digging apparatus concerned comprises a powered rotating digging wheel having a plurality of digging projections or cutter tips which dig out the material when applied thereto as the wheel is rotated under power.

One form of known digging apparatus is a trencher which is a trench digging machine comprising a vehicle and the digging wheel propelled by the vehicle along the ground to dig a trench therein having a length which increases as the vehicle and digging wheel progress. The vehicle may run on wheels at least some of which are driven, and/or it may be a track laying vehicle running on driven endless tracks.

In a known trencher the digging projections or cutter tips are mounted on the periphery of the digging wheel and project outwardly from that periphery. The digging wheel lies in a substantially vertical plane and coincides with the plane in which the trench being dug lies., The digging wheel normally is of large diameter for example at least one metre in diameter, and can be larger for example two metres or so. Directly attached to the digging wheel is a large diameter ring gear having gear teeth around its interior. This ring gear is centred on the axis of rotation of the digging wheel, and is secured to the wheel, at or adjacent to the outer periphery of the digging wheel. At least one driving pinion gear wheel having teeth around its outer periphery meshes with the internal teeth on the ring gear which thus surrounds the driving pinion(s).The or each driving pinion is driven by respective motor means which, through the ring gear, drives the digging wheel. This form of drive has at least two drawbacks. One is that excavated material entering the gaps between the internal teeth of the ring gear tends to remain trapped there, at least partly due to the effect of centrifugal force, and so the retained excavated material acts as a harsh grinding powder where the ring gear and pinion(s) mesh. This can cause serious and rapid wear of the teeth of the meshing gear wheels. The other drawback is that because the ring gear has a large diameter (almost as large as the digging wheel) and the or each driving pinion is relatively small, the rotational speed of the digging wheel is not as fast as is sometimes desirable.

An object of the invention is to provide a construction of digging apparatus wherein the digging wheel is driven in manner which avoids or mitigates the above mentioned drawbacks such that risk of wear of meshing gear wheels in the driving system is reduced, and the speed of rotation of the digging wheel can be increased above what would be normal in a known driving system.

According to the invention a digging apparatus to dig material from the ground comprises a powered rotating digging wheel having a plurality of digging projections or cutter tips which dig out the material when applied thereto as the digging wheel is rotated under power, a first gear wheel centred on the axis of rotation of the digging wheel and being mounted fast with said digging wheel, said first gear wheel having gear teeth around its outer periphery meshing with gear teeth around the outer periphery of at least one second gear wheel or pinion such that the first gear wheel and the pinion mesh at a position between the axes of rotation of the first gear wheel and the pinion, and motor means to rotatably drive the pinion.

Because the teeth on the first gear wheel and pinion are outer teeth it is easier for gritty excavated material from the digging to be ejected radially outwardly from both the gear wheels which reduces the chance of gear teeth wear. Also, because the pinion can be the same driving pinion as was used in known apparatus but is now meshing with teeth on the said first gear wheel that first gear wheel is of smaller diameter than the ring gear used in the known apparatus, and thus that first gear wheel has less gear teeth than are on the known ring gear. This means the driving pinion drives the first gear wheel at a faster angular velocity than the known ring gear, and hence the first gear wheel drives the digging wheel: at that faster angular velocity.

The invention will now be further described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is a side elevation of digging apparatus, in the form of a trencher, formed according to the invention; Fig. 2 is an elevation, from the opposite side, of a fragment of the apparatus in Fig 1; Fig. 3 is a fragmentary view similar to Fig. 2 but on a larger scale, and Fig. 4 is a section on line IV-IV in Fig. 3, but on a larger scale.

With reference to the accompanying drawings, a trencher is shown at 2 comprising a ground running vehicle 4 towing a powered, digging wheel 6 which is preferably of steel. The vehicle 4 can be powered by an internal combustion engine (not shown) which drives ground running wheels 8 to travel over surface 10 of the ground 12. A vertical frame 14 is secured to the rear of vehicle 4. Another frame 16 is horizontally pivotted at 17 to the frame 14. Depending from the frame 16 are two sturdy, horizontally spaced brackets 18 and 20 having mounted thereon at 22 an axle arrangement of the digging wheel 6. The digging wheel 6 can be of any suitable construction and has mounted, at its outer periphery 23, in any suitable way outwardly projecting suitable digging projections or cutter tips 24.In the example, the digging wheel 6 is formed by a web or solid disc 26 extending from a hub or centre portion holding the axle arrangement 22 to the outer periphery 23. But the wheel 6 could have a disc portion 26 which is appertured or be substituted by a spoke arrangement extending from a hub and carrying a circumferentially extending peripheral rim part on which the cutter tips 24 are mounted.

The digging wheel 6 which rotates in a substantially vertical plane, can be raised or lowered to a desired position by fluid powered jacks 27 and 28. As the vehicle 4 progesses along the ground 12, the digging wheel 6 following the vehicle digs a trench 30, and excavated spoil 32 piles up on the surface 10 alongside the trench and also in front of the digging wheel. A supporting foot 34 is horizontally pivotted at 36 to the frame 16 behind the digging wheel 6 and rests on a floor 38 of the trench to support the digging wheel. A fluid powered jack 40 is provided to swing the foot 34 away from the digging wheel 6 and to return the foot to its supporting position.

The engine driving-the vehicle 4 can also drive pump means included in the vehicle to provide hydraulic or pneumatic power to operate the jacks 26, 28 and 40.

As shown, with particular reference to Figs. 3 and 4; in which the bracket 20 is shown in phantom lines, a ring or cylindrical flange 42 centred on the axis of rotation of the digging wheel 6 is welded at 44 and 46 direcly to a side of the wheel, in this case directly to a side of the disc 26. The ring 42 serves to radially position a ring gear wheel 50 having gear teeth 52 at its outer periphery. A plurality of bolts 54 secure the gear wheel 50 to the disc 26. The gear wheel 50 is also welded at 56 to the ring 42. thus the gear wheel 50 is mounted fast with the digging wheel 6, and is directly mounted fast with a side of the digging wheel. A pinion gear wheel 58 meshes with the gear wheel 50. The pinion 58 has a driving shaft 60. Thus the gear wheel 50 and the pinion 58 mesh at a position between axis of rotation of the shaft 60 and the axis of rotation (at the axle arrangement 22) of the gear wheel 50. A motor 62 mounted on the flange 20 has a driving output shaft 60 driving the pinion 58 mounted thereon. In turn the pinion 58 drives the digging wheel 6 via the gear wheel 50. The motor 62 can be an hydraulic or pneumatic powered motor or may be powered in. some other way, for example it may be an electric motor.

The position of the motor 62 on the flange 20 is variably adjustable allowing the motor and driving shaft 60 and pinion 58 to be moved along an arcuate slot 64 in the flange 20, through which slot the shaft 60 passes. Releasable motor clamping arrangements each 'comprising a clamping flange 66 or 68 and a respective clamping bolt 70 or 72 clamp and hold the motor 62 in a desired position along the slot 64. In this way correct meshing of the pinion 58 with the gear wheel 50 can be ensured. In an alternative the aforesaid clamping arrangements can be subsituted by mounting the motor 62 on an arm pivotably mounted on the flange 20 to which the arm can be locked to hold the motor at a desired position along the slot 64.

A stationary cover 74 having a generally arcuate peripheral wall 76 encloses a lower portion of the gear wheel 50 in an effort to reduce the chance of excavated material coming into contact with that gear wheel. Bolts 78 hold the cover 74 on the bracket 20.

The gear wheel 50 and pinion 58 can be made of special hard steel.

The pinion 58 can be removably mountable on the driving shaft 60. Thus a larger or smaller pinion 58 can be used, the position of the motor 62 and shaft 60 being adjusted by means of the slot 64 and motor clamping arrangements so that the digging wheel may be driven faster or slower according to the size of pinion 58 selected. Also a ring gear 80 having gear teeth on its inner periphery can be secured to the wheel disc 26 by means of bolts in holes 82 in the wheel disc, so that the ring gear is located adjacent to the periphery 23 of the digging wheel 6. The arrangement can be such that the position of motor 62 can be varied to disengage the pinion 58 from the gear wheel 50 and engage it with the ring gear 80 to drive the digging wheel 6 through a lower ratio and thus more slowly.

If desired there may be a plurality of pinions 58 simultaneously meshing with the gear wheel 50.

Each of these pinions can be driven by a respective drive shaft 60 each driven by a respective motor 62 each mounted as described above side by side on the flange 20, said drive shafts 60 being substantially parallel.

In some circumstances the digging wheel 6 can be driven in an opposite direction to the anti-clockwise direction indicated by the arrow in Fig. 1.

Claims (10)

Claims

1. A digging apparatus to dig material from the ground comprising a powered rotating digging wheel having a plurality of digging projections or cutter tips which dig out the material when applied thereto as the digging wheel is rotated under power, a first gear wheel centred on the axis of rotation of the digging wheel and being mounted fast with said digging wheel, said first gear wheel having gear teeth around its outer periphery meshing with gear teeth around the outer periphery of at least one second gear wheel or pinion such that the first gear wheel and the pinion mesh at a position between the axes of rotation of the first gear wheel and the pinion, and motor means to rotatably drive the pinion.

2. A digging apparatus as claimed in Claim 1, in which said first gear wheel is directly mounted on a side of said digging wheel.

3. A digging apparatus as claimed in Claim 1 or Claim 2 in which a first gear wheel is a ring gear surrounding a circular supporting flange mounted on the digging wheel.

4. A digging apparatus as claimed in any one preceding claim, in which the position of the pinion is adjustable whereby the axis of rotation of said pinion can be moved towards and away from said first gear wheel.

5. A digging apparatus as claimed in Claim 4, in which said pinion is interchangeable with another pinio'n of a different size to mesh with said first gear wheel and be driven by said motor means.

6. A digging apparatus as claimed in Claim 4, in which a ring gear mounted on the digging wheel and having gear teeth on its inner periphery and surrounding said pinion can be selectively enmeshed with the pinion in preference to said first gear wheel.

7. A digging apparatus as claimed in any one preceding claim, in which a cover is mounted over at least a portion of the first gear wheel.

8. A digging apparatus as claimed in any one preceding claim, in which said digging projections or cutter tips project from an outer periphery of the digging wheel.

9. A digging apparatus as claimed in Claim 8 and in any one of Claims 1 to 7, in which the digging apparatus is a trencher.

10. A digging apparatus in the form of a trencher substantially as hereinbefore described with reference to the accompanying drawings.