US1808948A - Percussive hand tool - Google Patents

Description

Patented June 9, 1931 UNITED STATES LOUIS FLUHR AND ANTHONY VERHAAR, OF BRUSSELS, BELGIUM rnncussrvn HAND TOOL Application filed April 24, 1930, Serial No. 447,078, and. inv Belgium July 20, 1929.

The present invention has relation to a percussive hand hammer, in which the tool 1s actuated to have a rapid striking movement combined with an intermittent rotary movement.

According to the invention, a shaft mounted in the casing of the hammer, is rotated either manually or by means of an electrlc motor; on this shaft is mounted a cam wheel engaging a lever integral with the striker; this lever is pivoted to. the casing of the hammer and comprises a finger to be engaged by the projections of said cam wheel and a second spring controlled finger, which compresses said spring when the lever is rotated from its normal position under the actlon of said cam wheel; the expansion of said spring brings the lever back to its normal position and thereby communicates to the striker, integral with said lever, the percussion movement which it has to transmit to the tool; the tool is, moreover, provided with a ratchet wheel, in which engages a pawl, controlled by the above-mentioned lever, in such a way as to impart a rotary movement in one direction to the tool at every stroke of the striker.

An embodiment of the invention will be described hereafter with reference to the figures of the accompanyingdrawings, which are given merely by way of example.

Fig. 1 is a vertical sectional view of the hammer;

Fig. 2 is an elevation view of the striker in the direction of the arrow Z;

Fig. 3 is a vertical sectional view on line X-Y of Fig. 1;

Fig. 4 is a view of a crank for manually driving the percussive hammer.

lVith reference to these figures, the apparatus comprises a casing 1, provided with a which shaft is keyed a suitably bent lever 34,

carrying at one of its ends a conveniently shaped striker 7 A second shaft 12 is also mounted for rotation in the support 4:, on which shaft are mounted a cam wheel 11 and a crank 13 (Fig. 4, not illustrated in Fig. 1),

which may be actuated, either by an electric motor or by hand, with the help of a handle 14 provided with a pin 15 mounted in the crank 13. r

The lever 34 is provided with a finger a, on which. periodically strike the projections of the cam wheel 11, and with an arm 0, controlled by a spring 16, which is pressed between said arm 0 and a washer forming part Y of a shank 17; this spring can be more or less tightened by means of a wing nut 18. The lever 34 further comprises an arm I) acting upon a pawl 24.

The apparatus comprises moreover a tool holder 22, secured by means of a pin 23 to the shaft of a ratchet wheel 19 coacting with the pawl 24. The ratchet wheel 19 and its shaft are adapted to rotate in a bearing 20, which is secured to the casing l by means of screws 21. The pawl24: is pressed against the toothed periphery of the ratchet wheel 19 by a leaf spring 25 (Fig. 3), fixed to the pawl by means of the pin 27. This spring presses at the same time against the ratchet wheel a pawl 28 adapted to oscillate about the pivot screw 29. The casing may be closed by means of two lids 30 and 31 assembled by means ofscrews 32 and nuts 33.

The striker is also provided witha screw 8 for adjusting purposes, which is fixed by means of a. lock screw 9. a

The shaft 12 of the cam wheel 11 is pro- Vided, on the one hand at g, with a right hand thread, on which is screwed the end part 6 of the crank 13, and, on the other hand at cl, with a left hand thread, on which may be screwed a port-ion f of the crank 13. The object of this arrangement is to allow of placing this crank on either side of the apparatus.

The working of the apparatus is as'follows when the crank 13 is rotated, the cam wheel 11 acts upon the finger aof the striker 7. The arm 0 of the striker is subjected to the action of the spring'16, whilst the arm 6 acts upon the pawl 24, which rotates the ratchet wheel 19 and, thereby, the tool fixed in the sleeve or holder 22. As soon as the finger a has been freed, the striker is violently projected against the ratchet wheel and the shock is transmitted to the tool. During this stroke,

the pawl 24 has come back to its first position, whereas the pawl 28, engaging the ratchet wheel, has prevented the latter from rotating in the opposite direction. If the rotation of 5 the crank is continued, the hereabove described movements will be repeated, so that the tool receives a shock after each rotation.

We claim: 1. A percussive hand hammer, comprising a casing, a bent lever pivotally mounted in said casing, a striker integral with said lever, a cam wheel mounted for rotation in said casing and adapted to engage said lever, a spring acting upon said lever for bringing it back to its normal position after engagement by said cam and for imparting the required impulsion to the striker, a pawl pivotally connected to said lever, a ratchet wheel integral with the tool and adapted to be ro- 9:,tated by said pawl, a second pawl preventing the rotation of the ratchet wheel in the opposite direction, anclthe striking tool receiving percussive movements from the striker and intermittent rotary movements from the 5 ratchet wheel.

7 2. A. percussive hand hammer, comprising a casing, a bent lever pivotally mounted in said casing, a striker integral with said lever, a cam wheel mounted for rotation in said casing and adapted to engage said lever, a shank, a coil spring pressed between a projection of said lever and a washer of said shank and compressed when the lever is engaged by said cam wheel, means to shift saidshank and thereby to regulate the tension of the spring, a pawl pivotally connected to said lever, a ratchet wheel integral with the tool and adapted to be rotated by said pawl, a second pawl preventing the rotation of the ratchet ;iwheel in the opposite direction, and the striking tool receiving percussive movements from the striker and intermittent rotary movements from the ratchet wheel.

In testimony whereof we signed hereunto 5 0111 names.

LOUIS FLUHR. ANTHONY VERHAAR.

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