GB2108882A

GB2108882A - Ratchet screwdriver

Info

Publication number: GB2108882A
Application number: GB08133553A
Authority: GB
Inventors: Wing Wong Siu
Original assignee: CHING WAH METAL WARE FACTORY L; CHING WAH METAL WARE FACTORY Ltd
Current assignee: CHING WAH METAL WARE FACTORY L; CHING WAH METAL WARE FACTORY Ltd
Priority date: 1981-11-06
Filing date: 1981-11-06
Publication date: 1983-05-25

Abstract

A ratchet screwdriver comprises a manually grippable handle 10, a sleeve 2 freely rotatably mounted within the handle and projecting axially from one end thereof, a chuck within the sleeve for non-rotatably mounting a blade 17 therein, a gear ring 4 having internal teeth secured within the handle, a core member 3 freely rotatably mounted within the gear ring 4 and non-rotatably connected to the sleeve 2, and ratchet drive means for selectively connecting the core member to the gear ring to transmit torque in one direction of rotation and to permit rotation in the other direction, and vice versa. The ratchet drive means includes a claw member 7 pivotally mounted on the core member 3 and having two teeth alternatively engageable with the internal teeth on the gear ring, and a control switch assembly 23 for pivoting the claw member 7 so that one or the other of its teeth selectively engages the internal teeth of the gear ring. <IMAGE>

Description

SPECIFICATION Ratchet screwdriver This invention relates to a ratchet screwdriver.

A ratchet screwdriver according to the invention comprises a manually grippable handle, a sleeve freely rotatably mounted within the handle and projecting axially from one end thereof, means within the sleeve for non-rotatably mounting a blade therein, a grear ring having internal teeth secured within the handle, a core member freely rotatably mounted within the gear ring and non-rotataly connected to the sleeve, and ratchet drive means for selectively connecting the core member to the gear ring to transmit torque in one direction of rotation and to permit relative rotation in the other direction, and vice versa, the ratchet drive means including a claw member pivotally mounted on the core member and having two teeth alternatively engageable with the internal teeth on the gear ring, and a control switch assembly for pivoting the claw member so that one or the other of its teeth selectively engages the internal teeth of the gear ring.

An embodiment of a ratchet screwdriver according to the invention is shown by way of example in the accompanying drawings, of which: Figure 1 is a side view of the screwdriver, Figure 2 is an end view of the handle, Figure 3 is a cross-sectional side view of the screwdriver, and Figures 4, 5 and 6 are respectively crosssectional views taken on the lines lV-lV, V-V and VI--VI in Figure 3.

Referring to the drawings, the ratchet screwdriver shown comprises a manually grippable handle 10 and a sleeve 2 freely rotatably mounted within the handle and projecting from the forward end thereof. Mounted within the handle 10 is a grear ring 4 having internal teeth.

The exterior of the gear ring is formed with two diametrically opposite projections 12 which are received within corresponding grooves in the handle 10 so that the handle 10 and the gear ring 4 are relatively non-rotatably connected. The gear ring 4 includes an axially forwardly projecting hub portion 14 which serves as a bearing for rotatably supporting the sleeve 2. A core member 3 is freely rotatable within the gear ring 4. The gear ring 4 and the core member 3 are connected together by a part-annular plate 5 which is received within a corresponding slot in the hub portion of the gear ring and projects into an annular groove 1 5 around the core member 3 so that the core member and the gear ring are freely rotatable relative to one another but are locked against relative axial displacement.The sleeve 2 is connected to the forward end of the core member 3 by splines 16, and incorporates a chuck having a retaining spring 1 for gripping one of a number of interchangeable screwdriver blades that may be inserted therein. A blade 1 7 having a conventional chisel tip is shown.

A claw member 7 is pivotally mounted on an axle 6 secured in the core member 3 radially offset from the axis thereof. The axle 6 is parallel to the longitudinal axis 1 8 of the screwdriver so that the claw member pivots in a plane transverse to the axis. The claw member 7 is symmetrical about a median plane 1 9 containing the axis 1 8 of the screwdriver and the axis of the pin 6, and has two teeth 20 opposed to the internal teeth on the gear ring 4, one tooth on each side of the plane of symmetry. The radially inner face 21 of the claw member 7 is arcuate and a spring plunger 8 is in wiping contact with such face.

The spring plunger 8 forms part of a control switch assembly 23 which consists of a stem 24 rotatably mounted in the core member 3 on the axis 1 8 thereof, and a disc 25 recessed with respect to the plane of the end face 11 of the handie. The disc has a raised diametrical rib 26 to assist in manipulation thereof. The spring plunger 8 is mounted in a blind radial bore in the stem 24.

The claw member 7 is pivotable over a limited angular range, the end positions of which are set by the engagement of the respective teeth 20 with the internal teeth on the gear ring 4. The position which the claw member assumes is determined by control switch 23. In a central position of the switch in which the axis of the spring plunger 8 intersects the axis of the pin 6 namely the pivotal axis of claw 7, neither of the claw teeth 20 is engaged with the internal teeth of the gear ring 4.

Thus in this central or neutral position manual rotation of the handle 10 is not transmitted to the core member 3 and hence to the sleeve 2 and the screwdriver blade 1 7. The blade can however be turned by gripping and rotating the sleeve 2.

If the switch 23 is then turned anti-clockwise, the spring splunger 8 pressing against the radially inner face of the claw causes the claw to pivot on the pin 6 until the left tooth 20 (Fig. 6) engages with teeth of the gear ring 4. If then handle 10 is gripped and turned clockwise, the forces acting between the teeth of the ring 4 and the claw tooth 20 tend to supplement the resilient bias exerted by the spring plunger 8 and to lock the claw tooth 20 in engagement with the gear ring teeth. Torque applied to the handle 10 is thus transmitted through the gear ring 4, the claw 7, the pin 6 and the core member 3 to the sleeve 2 and the screwdriver blade.If then the direction of the applied torque is reversed, i.e. the handle 10 is rotated anti-clockwise, the camming action of the gear ring teeth on the claw tooth 20 overcomes the bias exerted by the spring plunger 8 and the claw 7 is pivoted anti-clockwise until the tooth 20 slips out of engagement with the gear ring teeth.

The desired ratcheting action is thus obtained.

It will be appreciated that the converse action is obtained when the switch member 23 is rotated clockwise through the neutral position to pivot the claw member anti-clockwise so that the righthand tooth 20 thereof engages with the internal teeth of the gear ring 4. in this position torque applied by rotating the handle 10 anti-clockwise is transmitted to the blade, and a ratcheting action is obtained upon rotating the handle 10 clockwise.

It will thus be seen that the disclosed arrangement comprises selectively settable oneway drive means for rotatably connecting the handle and the sleeve. The switch is recessed with regard to the end face of the handle, the furthest axial extent 26 of the rib being substantially in the same plane as the end face of the handle, so that when axial pressure is applied to the end face of the handle the possibility of inadvertently operating the switch member 23 during use of the screwdriver is lessened.

Claims

1. A ratchet screwdriver which comprises a manually grippable handle, a sleeve freely rotatably mounted within the handle and projecting axially from one end thereof, means within the sleeve for non-rotatably mounting a blade therein, a gear ring having internal teeth secured within the handle, a core member freely rotatably mounted within the gear ring and nonrotatably connected to the sleeve, and ratchet drive means for selectively connecting the core member to the gear ring to transmit torque in one direction of rotation and to permit relative rotation in the other direction, and vice versa, the ratchet drive means including a claw member pivotally mounted on the core member and having two teeth alternatively engageable with the internal teeth on the gear ring, and a control switch assembly for pivoting the claw member so that one or the other of its teeth selectively engages the internal teeth of the gear ring.

2. A ratchet screwdriver according to Claim 1, wherein the gear ring is secured to the handle by means of external projections on the ring which are received within corresponding grooves in the handle.

3. A ratchet screwdriver according to Claim 1 or Claim 2, wherein the gear ring includes an axially forwardly projecting hub portion which serves as a bearing for rotatably supporting the sleeve.

4. A ratchet screwdriver according to Claim 3, in which the gear ring and the core member are connected together by a part-annular plate which is received within a corresponding slot in the hub portion of the gear ring and projects into an annular groove around the core member so that the core member and the gear ring are freely relatively rotatable but are locked against relative axial displacement, and means non-rotatably connecting sleeve and the core member.

5. A ratchet screwdriver according to any one of the preceding Claims, wherein the claw member is pivotally mounted on an axle secured in the core member radially offsetfrom.the axis thereof for pivotal movement in a transverse plane, the claw member is symmetricai about a median plane containing the axes of the screwdriver and the axle, having one said tooth on each side of the plane of symmetry, and the claw member has a radially inner face which is arcuate.

6. A ratchet screwdriver according to Claim 5, wherein the control switch assembly includes a stem rotatably mounted in the core member of the axis thereof, means accessible at the exterior of the handle for manually rotating the stem, and a spring plunger mounted radially in the stem and in wiping contact with the arcuate radially inner face of the claw member whereby rotation of the stem from a first to a second position and vice versa causes the claw member to pivot on the axle so that first one and then the other tooth is caused to engage with the internal teeth on the gear ring, to transmit rotation of the gear ring to the core member in one direction and to allow a ratcheting action upon rotation in the other direction.

7. A ratchet screwdriver according to Claim 6, wherein the stem is capable of assuming a neutral position in which the axis of the spring plunger intersects the pivotal axis of the claw and in which neither of the claw teeth is engaged with the internal teeth of the gear ring so that manual rotation of the handle is not transmitted to the core member.

8. A ratchet screwdriver according to Claim 6 or Claim 7, wherein the exteriorally accessible means substantially do not project beyond the axial end face of the handle.

9. A ratchet screwdriver substantially as hereinbefore described with reference to the accompanying drawings.