US 3779567 A
This disclosure relates to a retainer for the reciprocating chisel of a chipping hammer, of the snap-over, spring yoke type.
Description (OCR text may contain errors)
United States Patent [191 Boyd Dec. 18, 1973  TOOL RETAINER FOR CHIPPING 1,613,139 1/1927 Skaer 279/19.1 HAMMERS 1,719,079 7/1929 Pearson 279/19.1 1,776,922 9/1930 Naismith 279/19.1  Inventor: James C. Boyd, c/o T001 Sales &
Service Co., 1137 Electric Ave., East Pittsburgh, 5112 Primary ExaminerTravis S. McGehee  Filed; June 27 1972 Assistant Examiner-Z. R. Bilinsky Attorney-Wm. Henry Venable 211 App]. No.2 266,694
 US. Cl. 279/19.1 51 Im. Cl B25d 17/10 ABSTRACT  Field of Search 279/191, 19.2, 19,3,
279/l9.4, 19.5, 19.6, 19.7, 19 This disclosure relates to a retainer for the reciprocating chisel of a chipping hammer, of the snap-over, [5 6] References Cited spring yoke type.
UNITED STATES PATENTS 1,632,837 6/1927 1 Claim, 9 Drawing Figures Hansen 279/19.1
PATENTEUHED 18 ms 3. 779.567
- SHEET 2 (IF 2 I TOOL RETAINER FOR CHIPPING HAMMERS BRIEF SUMMARY OF THE INVENTION The object of this invention is to provide a safety retainer for chipping hammer chisels which is simple, economical in cost, has a long life, and facilitates easy removal and entry of chisels. In brief, it-is comprised of three components: an adapter cup fitting the tapered end of a chipping hammer housing, means for securing the adapter cup to the hammer housing, and a spring yoke pivoted to the sides of the adapter to swing around the end of the cup into a latched position at which it embraces the chisel shank ahead of the shoulder of the chisel, thus retaining the chisel within the hammer until rotated out of the latched position.
BRIEF DESCRIPTION OF DRAWINGS An embodiment of my invention is illustrated in the accompanying drawings, in which,
FIG. 1 shows my tool retaining attachment applied to a chipping hammer with the safety latch in tool retaining position.
FIG. ,2 is an isometric view of a chipping hammer body prepared for assembly of the tool retaining attachment thereon. I
FIG. 3 is an exploded view of my attachment in unlatched position with a chis'el being inserted into or removed therefrom.
FIG. 4 shows the retainer spring which holds the attachment to the hammer housing.
FIGS. 5 and 6 are side and front views, respectively, of the tool guide adapter component.
FIGS. 7, 8 and 9 show the spring retainer yoke component.
DETAILED DESCRIPTION As is well known in the art, the most commonly used chipping hammer and chisel assembly employs a'chisel tool 10 having an oval shaped shoulder 11 and a hexagonal shank lla. The long axis of the oval 11 is parallel to the cutting edge 14 of tool 10. This tool is inserted into the hammer 13 through a conventional retainer which has an oval shaped mouth, the shank Ila extending into the mouth 12 of the hammer and the shoulder 11 being between this mouth 12 and the oval mouth of the retainer. The tool is then rotated 90 where it is locked by a snap action latch in the conventional retainerflso that the oval shoulder 11 will not pass through the mouth of the retainer. The tool It) is twisted 90 against the snap action latch to line up the oval of the shoulder with the oval mouth of the retainer for removal, as when changing tools, The safety retainer hereinafter described is safer, lighter, faster for changing chisels and more economical both in initial cost and length of service life than other safety retainers now on the market.
My invention is extremely simple. It is comprised of only three components. These are a tool guide adapter number 15, a spring locking ring 16, and a spring latch yoke 17, shown in assembled position in FIG. 1 on a chipping hammer housing 13 with the tool 10 inserted therein. The hammer housing 13 in FIG. 1 is shown with the handle component removed; with the handle it appears as shown in FIG. 2. v
The tool guide adapter member is a cup shaped part 15 having a tapered inside bore 18 (see FIG. 5) machined to fit against the tapered end 19 of thehammer housing 13. A' circumferential groove 20 is machined in the bore 18, and a matching groove 21 is also machined around the tapered end of the hammer 13. A slotted opening 22 is provided in the adapter 15 registering with the groove 20 through which is inserted a helical spring locking ring 16 engaging both grooves 20 and 21 and securing the adapter cup to the hammer. Such matching grooves and helical spring locking ring are known and are shown as a preferred means for securing the cup 15 to the hammer, but any other conventional means, such as set screws, removable keys, etc., could be substituted if desired.
The adapter cup 15 terminates with a face 23 through which an oval shaped opening 24 is machined.
This opening 24 is the same shape as the shoulder 11 t of the tool, but slightly larger to permit the shoulder 11 to glide through it, and functions to keep the edge 14 of the tool 16 aligned as shown in FIGS. 1 and 3.
On each side of the rim of adapter cup 15 are provided trunions 25, at opposite ends of a diameter parallel with the long axis of the tool guiding oval 24. Adjacent each of these trunions a latch notch 26 is machined on the sides of the cup 15. Around the trunions 25 are fitted the eyes 27 of the tool retaining latch yoke 17, the details of which are illustrated in FIGS. 7, 8, and 9. This yoke is made of spring steel. Just ahead of the eyes 27 the yoke 17 has a short straight section 28 long enough to snap into the notches 26 of the adapter cup 15 when the yoke is rotated about the trunions 25, and the trunions 25 extend outwardly sufficiently to engage the eyes as the yoke expands laterally just before snapping into the notches 26, yet not too far to admit entry into the eyes 27 with the yoke expanded laterally within the elastic stretch of the spring material of which the yoke 17 is made.
The forward end of the yoke 17, swings around in front of the end of the cup 115, where the yoke is bent into a U-shaped hook 29. The inside radius 30 of hook 29 is slightly greater than the outside diameter of the shank of the tool MD and the yoke has short'parallel straight side sections 311. When a tool 10 has been inserted through the oval openings 24 of the cup 15 and 12 of the air hammer housing 13, with the shoulder 11 inside the housing, the yoke 17 is rotated around the trunions 25 until its straight sections 28 snap into the notches 26 and the hook 29 embraces the tool shank on the two sides which have the projections of the shoulder 1111, thus preventing the tool from removal from the hammer by blocking passage for the shoulder 11 beyond the hook 29 of the yoke 17.
II. A tool retainer attachment for chipping hammer chisels having an oval shaped shank shoulder, said attachment comprising in combination a hammer terminal cup having a tapered bore adapted to fit over the end of a chipping hammer housing, said cup having an axial tool guiding oval shaped opening through its face admitting the entry and withdrawal of said oval shaped shank shoulder of a chisel, means releasably for securing said terminal cup to the hammer housing in fixed position, a pair of trunions projecting laterally from said cup adjacent its rim, said trunions being oppositely located on a diameter parallel to the long axis of said oval shaped opening, a pair of notches in the side of said cup adjacent to said trunions, and a spring yoke pivotally mounted on said trunions to rotate into latched engagement with said notches, the forward portion of said spring yoke extending beyond the end of said cup in the form of a hook embracing said tool shank on opposite sides at a diameter parallel to the long axis of said axial oval opening in the face of said terminal cup.
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