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Title:
HAND TOOL
United States Patent 3717053
Abstract:
A hand tool suitable for adjusting the tappet clearance of overhead valves in an internal combustion engine in which a member for engaging the nut of the valve and a member for engaging the screw of the valve are attached to parts which are receivable one within the other, and indexing means are provided between the parts to locate the parts in any one of a number of equiangularly spaced positions relative to one another.


Inventors:
STURGES F
Application Number:
05/059997
Publication Date:
02/20/1973
Filing Date:
07/31/1970
Assignee:
S.P.Q.R. Engineering Limited (Rowlands Castle, Hampshire, EN)
Primary Class:
Other Classes:
81/13
International Classes:
B25B13/06; B25B13/02; B25B13/46; B25B13/56; B25B15/00; B25B15/04; B25B27/30; F01L1/20; (IPC1-7): B25B13/48
Field of Search:
81/3F,55,13 7
View Patent Images:
US Patent References:
2736220N/A1956-02-28Kamuk
1654319Tappet-adjusting tool1927-12-27Brown
Foreign References:
DE703429C1941-03-08
Primary Examiner:
Riordon, Robert C.
Assistant Examiner:
Parker Jr. V, Roscoe
Claims:
I claim

1. A hand tool comprising a tubular member having a nut engaging part at one end thereof, an adjustment member carrying a part for engagement with a screw, the adjustment member being partly receivable in the tubular member from the other end thereof, indexing means acting between a part of the tubular member and a part of the adjustment member, to locate the adjustment member in any one of a plurality of equiangularly spaced locations relative to the tubular member while allowing relative axial adjustments and in which the adjustment member is formed with a skirt which fits over said other end of the tubular member, and the indexing means includes splines formed in the internal face of the skirt and a plunger member in the form of a roller flexibly carried by the tubular member for engagement with the splines.

2. A hand tool comprising a tubular member having a nut engaging part at one end thereof, an adjustment member carrying a part for engagement with a screw, the adjustment member being partly receivable in the tubular member from the other end thereof, and indexing means acting between a part of the tubular member and a part of the adjustment member, said parts being receivable one within the other, and the indexing means acting to locate the adjustment member in any one of a plurality of equi-angularly spaced locations relative to the tubular member while allowing relative axial adjustment and in which the adjustment member has a drive part, coupling means coupling the drive part to the part for engagement with the screw, the coupling means being arranged to transmit a positive drive in one direction and a slip drive in the other direction so that only a predetermined limited force can be transmitted in said other direction.

3. A tool according to claim 1 in which the sides of the splines over which the plunger member moves during the clockwise rotation of the adjustment member are less sharp than the sides over which the plunger member moves during the anti-clockwise rotation of the adjustment member.

4. A tool according to claim 2 in which the indexing means includes splines on one of the tubular member and the adjustment member and a plunger member in the form of a roller carried by the other of the tubular member and the adjustment member engaging the splines.

5. A hand tool comprising a tubular member having a nut engaging part at one end thereof, an adjustment member carrying a part for engagement with a screw, the adjustment member being partly receivable in the tubular member from the other end thereof, indexing means acting between a part of the tubular member and a part of the adjustment member, said parts being receivable one within the other and the indexing means comprising splines on one of the tubular member and the adjustment member and a plunger carried by the other of the tubular member and the adjustment member and acting to locate the adjustment member in any one of a plurality of equi-angularly spaced locations relative to the tubular member while allowing relative axial movement, the plunger and splines being continuously in engagement and being so arranged as to give a greater resistance to relative turning of the tubular member and the adjustment member in one direction than in the other direction.

6. A tool according to claim 5 in which the plunger member is carried on a circumferentially extending flexible arm.

7. A tool according to claim 2 in which the coupling means comprises a spring loaded annular ratchet.

8. A tool according to claim 6 in which the flexible arm extends circumferentially through at least 180° and is free except at its base.

9. A tool according to claim 1 in which the indexing means includes a bushing carried at said other end of the tubular member and having a portion cut away intermediate of its end and partially around its circumference to provide a flexible arm, adjacent the end of which is carried a roller engaging in splines on the adjustment member.

10. A tool according to claim 4 in which the plunger member is so mounted that it gives a greater resistance to relative turning of the tubular member and the adjustment member in one direction than in the other direction.

11. A tool according to claim 1 in which the part for engaging with a screw is a screwdriver having a shaft which is flexible.

12. A tool according to claim 7 in which the drive part comprises a cap coupled to the remainder of the adjustment member with a screw which also compresses a spring loading the ratchet with a predetermined force.

Description:
BACKGROUND OF THE INVENTION

This invention relates to a hand tool and is particularly although not exclusively concerned with such a tool that combines the functions of a spanner and screwdriver for adjusting the tappet clearance of overhead valves of an internal combustion engine.

Internal combustion engines for use in motor vehicles and for other purposes are now generally of the overhead valve type in which the valve stems are engaged by a tappet i.e., one end of a rocker arm the other end of which carries an adjusting screw engaging a push rod; the screw being held in place relative to the rocker arm by a lock nut. Adjustment of the tappets is an operation which must be carried out when the engine is initially assembled, from time to time during its normal operation and after any major engine servicing operation. In the past this adjustment has been carried out using a spanner, a screwdriver and a suitable feeler gauge, but it will be understood that such a method is clumsy and time consuming.

It is an object of the present invention to provide an improved hand tool particularly although not exclusively suitable for adjusting the tappet clearance of overhead valves of an internal combustion engine and which is sensitive in operation so that the valve clearance can be easily and accurately adjusted.

SUMMARY OF THE INVENTION

Accordingly the present invention provides a hand tool comprising a tubular member, one end of which is formed with a nut engaging part, an adjustment member carrying a part for engagement with a screw, the adjustment member being receivable in the tubular member from the other end thereof and indexing means acting between a part of the tubular member and a part of the adjustment member, which parts are receivable one within the other the indexing means acting to locate the adjustment member in any one of a plurality of equi-angularly spaced locations relative to the tubular member while allowing relative axial adjustment.

The indexing means preferably includes splines on the adjustment member engageable by a plunger carried by the tubular member and the part for engagement with a screw comprises a screwdriver blade formed at the foot of the adjustment member.

Preferably the adjustment member is formed with a skirt which fits over the other end of the tubular member the splines being formed on the internal surface of this skirt to engage a plunger member in the form of a roller flexibly carried by the tubular member.

The indexing may be arranged to give a greater resistance to relative turning of the tubular member and the adjustment member in one direction than in the other direction.

Preferably the indexing means includes a bushing carried at the other end of the tubular member and having a portion cut away intermediate of its ends and partially around its circumference to provide a flexible arm adjacent the end of which is carried a roller engaging in the splines. This arrangement is such that movement of the splines relative to the roller in one direction tends to flex the arm inwards and allow easy relative turning while movement of the splines in the other direction tends to flex the arm outwards and give considerable resistance to relative turning providing well defined steps from one spline to the next with the desired click.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

One embodiment of a hand tool, in accordance with the invention, will now be described, by way of example only, with reference to the accompanying drawings of which:

FIG. 1 is an axial section through a hand tool in accordance with the invention.

FIG. 2 is a section on a line 11--11 of FIG. 1, and

FIG. 3 is a section through the upper end of part of the adjustment member on the line 111--111 of FIG. 1.

The tool comprises a tubular member 1 provided at its lower end with a detachable nut engaging box spanner 2. A set of such spanners may be provided for use with the appropriate sized nuts. A handle 3 is secured to the tubular member 1 and may also be detachably connected if required for easy packing. An adjustment member is indicated generally at 4 and has a shaft 5 insertable into the upper end of the tubular member 1 as a close sliding fit in the lower part of a nylon bushing 6 which itself is a force fit within the upper end of the tubular member 1. The engaging surfaces of parts 5 and 6 form a self-lubricating bearing allowing easy turning and axial movement of the shaft 5 in the tubular member. The lower end of a plastics material shaft 5 has firmly secured thereto a metal extension shaft 7 the lower end of which is formed as a screwdriver blade 8. The screwdriver shaft is thus slightly flexible. The upper end of shaft 5, one end of which is formed with projections 10, has secured thereto a head indicated generally at 11 and forming part of the adjustment member. The head has a first part 12 in which the upper end of the shaft 5 is moulded and which has a depending skirt 13 in which the upper end of the tubular member 1 is received. The internal surface of the skirt is formed with equi-angularly spaced splines 14 while the outer surface is formed with ribs and grooves 15. The upper surface of part 12 is formed with an annular ratchet having four teeth 16 equi-angularly spaced and engaging with similar teeth formed on a similar annular ratchet 17 on the lower surface of the central portion of a cap 18 joining the second drive part of the head. The central area of the upper surface of the part 12 is formed with an upwardly extending projection 20 received in a bore 21 in the lower part of the cap, the projection 20 itself being formed with a bore 22 containing a bushing 23 to receive the end of a screw 24. The cap 18 is also formed with a bore 25 to receive the screw 24, the upper part 27 of this bore being enlarged to house a spring 28 located around the screw and compressed between the head of the screw and the base 29 of the enlarged bore. The screw is screwed down until a shoulder 30 thereof engages the top of the bushing 23 thus compressing the spring a predetermined amount to urge the cap and the part 12 together in an axial direction with a predetermined force. The cap 18 has a knurled exterior and its lower edge extends freely over the upper edge of part 12. The cap is formed with an annular groove 31 opening to its upper surface, and a cover plate 32 is located as a force fit over the central top portion of the cap to cover this groove and the head of the screw 24. The cover plate has four prongs 33, which extend to the base of the groove and have outwardly projecting teeth 34, located in windows 35 in the wall of the cap to prevent removal of the cover plate.

The bushing 6 has an upper part which forms an extension of the tubular member 1 having the same outer and inner diameters. A portion of this upper part is cutaway to provide a vertical slot 34' and a circumferential slot 35', the latter extending through just over 180° and having its base indicated at 36. Above slot 35 there is thus formed a flexible arm 37 the outer side of the end of which is provided with a part cylindrical groove 38. A plunger member 40 in the form of a cylindrical roller is located in the groove 38 so that its opposite side rests in one of the gaps between the splines 14. It will be appreciated that the splines and rollers 40 provide an indexing means locating the adjustment member in one of a number of discrete equi-angularly spaced positions relative to the tubular member. Clockwise rotation of the adjustment member in the direction of arrow 41 of FIG. 2 can be easily effected since such movement tends to push the arm 37 inwards and allow the roller to pass easily over each of the splines. However, anti-clockwise movement of the adjustment member pushes the roller 40 in a direction which urges the arm 37 outwardly to provide a greater resistance to the turning. The roller will thus jump from one groove to the next with a more positive action and a resulting click. The clicks are counted by the operator and provide a precise indication of how far he has adjusted the tappet. The sides of the splines up which the roller moves during the clockwise rotation are less sharp than the sides up which the roller moves during the anti-clockwise rotation of the adjustment member to enhance this effect.

A ring 42 around shaft 7, prevents complete separation of the adjustment member and tubular member so that roller 40 cannot drop out. The edge of the skirt 13 and the adjacent part of the tubular member are formed with a registering scale and datum line; the spacing of the splines 14 and therefore the gaps therebetween corresponding to the smallest divisions of the scale. The circumferential spacings of the spline and each division of the scale corresponds to a desired tappet clearance. For example each click may represent one thousandth of an inch tappet clearance. It will be appreciated that in order to calibrate the scale or to determine the spacing of the splines the number of threads per inch of the tappet screw must be known together with the ratio of the length of limbs of the rocker arm on each side of the rocker shaft. However, most manufacturers use the same thread on their tappet adjusting screws for all their engines and the ratio referred to above tends to be standardized so that although it may be necessary to produce a number of tools with different characteristics each tool can be used on a large number of engines. With an appropriate chart indicating the adjustment (i.e. number of clicks) required for different engines the same tool can be used on most engines by ignoring the scale on the tool.

In operation to adjust a tappet of an overhead valve internal combustion engine the spanner head 2 is first engaged over the tappet screw lock nut and the blade 8 is engaged with the screwdriver slot formed at the other end of the tappet screw, any disalignment of this slot being accommodated by flexing movement of the part 7 relative to the part 5. The operator then holds the adjustment member firmly whilst slackening the nut using the handle 3. The handle 3 is then held firmly and a clockwise rotary force, as seen from the top of the tool, is applied by hand to the cap 18 to screw down the tappet screw to zero gap. When the zero gap position is reached resistance to turning by the screwdriver shaft 7 will cause the teeth of the respective annular ratchets 16 and 17 to ride up one another compressing the spring 28; the greatest force exertable on the screwdriver in the clockwise direction is thus limited by the spring force when it is most compressed that is when the teeth have ridden up one another to their full extent before falling to engage a successive tooth. The ratchet, therefore, provides a slip drive means which cannot exert more than a predetermined drive force from the cap 18 to the screwdriver shaft 7 in the clockwise direction rotation. In this direction the resistance force given by the indexing means is a minimum. When a rotary force is applied in the anti-clockwise direction to the cap the teeth of the ratchet engage one another to form a positive non-slip drive. While still holding the handle 3 firmly the adjustment member is then turned in the anti-clockwise direction until the number of clicks has been heard corresponding to the desired tappet clearance. Confirmation of the correct tappet clearance being indicated on the scale acting between the adjustment member and the tubular member. The adjustment member is then held firmly in this position and the handle 3 turned to re-tighten the unit.