This invention relates to a device for operating the jaws of a chuck to open or close the jaws for location or removal of a drill bit or the like.

The tool presently used is a chuck key which locates in a radial pilot hole in the chuck and is rotated to rotate a gear ring of the chuck.

A disadvantage of using a key is that in theory the key should be inserted in turn into all three of the pivot holes in the chuck body in order to provide an even torque when tightening the jaws, but in practice this is not always done.

An other disadvantage of a key is that it is not permanently attached to the chuck and, therefore, can be easily misplaced or lost; in addition, the key and chuck openings are subject to wear.

An object of this invention is to obviate or mitigate the aforementioned disadvantages.

According to the present invention there is provided a device for operating a chuck which includes a set of jaws mounted within a rotatab e cylindrical barrel which extends from a sleeve having a bevelled gear ring, the barrel having three radial pivot holes for location of a chuck key to engage the bevelled gear ring, said device comprising a collar which locates around the barrel of the chuck and which supports at least one radially disposed pin mounting a bevel gear member for engagement with the chuck gear ring, said pin being locatable in a pivot hole in the chuck barrel so that when the collar is manually rotated relative to the sleeve the bevel gear member on the pin will rotate the chuck ring gear to open or close the chuck jaws.

Preferably, the collar carries three radially disposed pins at 120° disposition, each for location in a pivot hole of the chuck barrel.

Preferably also, the collar is of unitary construction having a front face, a rear face having an annular recess therein, at least one radial aperture through which a radial

pin extends and a bevel gear member located on the pin within the recess.

Preferably there are three radial apertures spaced at 120° to each other.

Preferably also, the or each pin is slidably carried in the collar so that the inner end can be withdrawn radially beyond the peripheral dimension of the chuck barrel to enable axial location of the collar therearound.

Preferably also, the pin is slidable through the bevel gear member.

Preferably also, a gear ring is carried in the recess of the collar facing rearwards and engaging the or each bevel gear member.

Preferably also, said gear ring is moveable relative to the collar.

Preferably, the bevel gear member is a single bevel gear and the annular gear ring within the collar is co¬ incident with the ring gear of the chuck.

Alternatively, the bevel gear member is a back-to-back gear whereof the radial inner gear engages the ring gear of the chuck and the radially outer gear engages the gear ring in the collar.

Preferably also, the perimeter of the collar is non circular, preferably substantially triangular.

In an alternative construction the collar is a composite assembly comprising a support ring to receive the radially outer end of the or each pin which is located in a pivot hole of the chuck barrel and which is in engagement with the chuck gear ring, and a drive ring which holdingly engages the support ring so that both rings can be manually rotated to rotate the barrel relative to the sleeve of the chuck to cause the chuck jaws to open or close.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:-

Fig. 1 is a rear elevation of a device according to the invention;

Fig. 2 is a fragmentation sectional side elevation of the device mounted on a chuck;

Fig. 3 is a view similar to Fig. 2 but showing the device in its operational mode, i.e. with a pin located in a pivot hole of the chuck;

Fig. 4 is a plan view of a pin and gear member; and

Fig. 5 is a side view of a chuck mounting the device according to another embodiment, the device being shown in section.

Referring firstly to Figs, l to 4, the device comprises a collar 10 which carries three radially disposed pins 11 spaced at 120° to each other and the pins 11 each carry a bevel gear member 12.

The collar 10 is of substantially equilateral triangular shape with a circular through hole 13 and a circular recess 14 in the rear face. The rear wall of the device therefore has narrow portions 15 between thick corner portions 16. The pins 11 extend through radial holes in the thick corner portions.

The pins 11 are slidable in the radial holes of the collar and slidable also relative to their respective gear members 12. This is to enable the position of the inner ends of the pins to be radially adjusted for a purpose hereinafter described. To more easily position the pins, and also to hold them against centrifugal forces during use, a "pen-clip" type of device 17 is attached to the outer end of each pin. Two notches 18, 19 are provided in a face of the corner portions, preferably on the rear face, the notch 18 being radially outward of notch 19.

Thus, when a pin 11 is in its outer, withdrawn position, the leg 20 of the clip 17 engages in notch 18; when the pin 11 is in its inner, active, position, the leg 20 engages notch 19.

The bevel gear member 12 diverges inwardly of the collar 10; at its outer end there is a flange 21 which engages the surface of the inner wall of the collar.

Within the recess of the device is an annular gear ring 22, the teeth of which face rearwards and engage the three

bevel gear members 12. The ring 22 thus prevents a gear member 12 falling by gravity off its pin should it tend to do so. The gear ring is not fixedly attached to the collar but 'floats', i.e. is free to rotate in conjunction with rotation of the gear members 12.

The device is for location on a chuck 25 as illustrated in Fig. 4. The chuck has a set of jaws 26 mounted within a rotatable cylindrical barrel 27 which extends from a sleeve 28 having a bevelled gear ring 29. The barrel 27 has three radial pivot holes 30 at 120° spaced locations, normally for location of a chuck key when it is desired to tighten or loosen the grip of the jaws 26 on a drill bit or the like.

The collar is located axially around the barrel moving relatively rearwards on to it so that the three bevel gear members 12 will engage the gear ring 29 of the chuck. At this stage, the pins 11 are in their "withdrawn" positions. The collar is rotatably adjusted if necessary until the pins can be pushed inwards, each into a pivot hole 30.

The collar 10, thus mounted in the chuck 25 can remain thereon as a permanent fixture but it can, if or when necessary be removed by freeing the legs 20 from notches 19 and withdrawing the pins to notches 18.

However, with the collar securely mounted on the chuck, all three gear members 12 are in engagement with the chuck gear ring 29 and also with the gear ring 22 within the collar recess.

In order to lighten or loosen the grip of the chuck jaws 26, the collar is manually rotated relative to the tool of which the chuck is a part. The substantially triangular shape of the collar provides for a better hand grip e.g. between the user's thumb and forefinger.

In practice, with the slack in the jaws taken up, and the tool held at the user's stomach, with one hand on the collar and the other on the body of the tool, a slight turn of the collar and tool in opposite directions should be sufficient to tighten the jaws, because all three gear members 12 contribute to generating the required torque.

The collar 10, the bevel gear members 12, the gear ring 22 and the clip 17 are all made of a plastics material (e.g. give example) only the pins 11 being of metal (steel) .

While it may be preferable to have a unitary collar, a composite collar assembly may be provided, and while it may be preferable to have a single bevel gear member on each pin, a pair of back-to-back gears may be provided. These features are illustrated in the embodiment shown in Fig. 5 wherein the collar assembly comprises a support ring 35 and a drive ring 36.

The support ring 35 in this embodiment is a composite unit comprising a mounting ring 35' and a retaining ring 35". These abutting surfaces co-operate so that both rings 35', 35" are rotatable together.

The retaining ring 35" has three recesses 37 in its forward face each to accommodate the outer half 38 of back- to-back bevel gear member 38/39 carried on a pin 40 which projects from each end thereof.

The drive ring 36 has a recessed rear face which has a rearwardly facing gear ring 41 to engage the outer bevel gear 38. The drive ring 36 also has a rearwardly extending sleeve 44 which overlies the bevel gears, the support ring 35 i.e. retaining ring 35' and mounting ring 35". Radially inward projections 43 on the sleeve 42 engage recesses in the mounting ring 35' to lock the drive ring 12 to the composite support ring 35.

The composite collar is mounted on the chuck 25 as follows:-

The mounting ring 35' then the retaining ring 35" are placed axially over the chuck sleeve 28. The three back-to- back gears 38/39 on the pins 40 is then positioned so that the inner end of each pin locates in a pivot hole 30 of the chuck, the inner gear 39 engages the gear ring 29 of the chuck and the outer gear 38 and outer end of the pin locate in the recesses 37 in the retaining ring.

The drive ring is then located in position and locked into the composite support ring 35.

The device as hereinbefore described, with reference to Figs. 1 to 5 or to Fig. 6, is advantageous over a chuck key:-

1) It can be permanently attached to the chuck,

2) as it makes simultaneously engagement with the chuck gear ring at three places, it produces maximum efficiency when applying torque.

3) The collar assists perpendicularity

4) changing drill bits is speeded up.

Although it is preferable, and desirable to use three gear/pins for the most efficient operation of the device, a device using one or two gear/pins would be able to operate although with less efficiency.