|Publication number||US2785710 A|
|Publication date||Mar 19, 1957|
|Filing date||May 3, 1954|
|Priority date||May 3, 1954|
|Publication number||US 2785710 A, US 2785710A, US-A-2785710, US2785710 A, US2785710A|
|Inventors||Jr Jesse R Mowery|
|Original Assignee||Walt Inc De|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (4), Referenced by (58), Classifications (17)|
|External Links: USPTO, USPTO Assignment, Espacenet|
March 19, 1957 J, ow JR 2;785,7l0
AUTOMATIC BRAKE FOR POWER TOOLS Filed may 3. 1954 fawn/vs TOOL ENTOR INV F|G.i JESSE R. MOWERY,JR.
United States Patent 7 2,785,710 7 AUTOMATIC BRAKE FOR POWER TOOLS Jesse R. Mowery, In, Lancaster, Pa., assignor to De Walt Inc., a corporation of Pennsylvania Application May 3, 1954, Serial No. 427,22i
Claims. (Cl. 143-157) This invention relates to an improved brake for a power saw, particularly a circular power saw.
In many circular power sa-ws, the saw is mounted directly on the motor arbor and operates at a relatively high R. P. M. When the power is turned off, the motor and saw continue to coast, presenting a safety hazard since an operator is apt to be careless when the power is oil". Furthermore, there is a time loss where one must Wait for the blade to stop before making adjustments.
It has accordingly long been recognized that brake means should be provided so that motor and blade may be stopped simultaneously with turning off the power. Accordingly, it is my invention to provide an automatic braking means engaging the circular blade itself.
It is another object of my invention to apply a brake to the blade itself to prevent throw off.
It is a further object of my invention that the brake is always applied when the power is off.
The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation may be understood by reference to the apparatus embodying my invention and shown in the accompanying drawing in which 1 illustrate a side elevation, partly, in section, of a power driven rotary tool in conjunction with an automatic braking device.
With reference to the drawing, 1 show a motor 1% driving a rotating shaft 12 supporting a woodworking tool such as a saw blade 14 secured thereon. The saw blade guard 16 is secured to the motor by fastening means 18. The guard 16 has the oppositely facing bores 26 formed in its side walls 22. The flange cylinders 24 are secured in bores 20. These cylinders 24 are adapted to hold the spring-loaded pistons 26 which are urged by the compression springs 28 toward the blade or tool 14. A piston shaft 3% protrudes through and slidingly engages a bore 32 formed in the head of each cylinder 24.
There is secured to the bight 4d of guard 16 a doubleacting solenoid or electromagnet 42 having armature plungers 44. When solenoid 42 is activated, the plungers 44 retract longitudinally toward each other into the solenoid. A lever 34 pivotally fulcrumed on lugs 36 secured to guard 16 connects the ends of plungers 44 to the outw wardly extending ends of piston shafts 39.
In operation, the solenoid 42 is connected across the terminals 11 of motor 14 so as to be energized when switch 13, connected in series between power lines and motor 19, is closed so as to cause operating current to pass through the motor windings (Fig. 2). When so energized the armature shaft-s 44 are moved toward each other, rocking the lever 34 to move pistons 26 and brake shoes 27 against the thrust of compression springs 28 and away from the tool 14.
When, on the other hand, the power is turned oif, the solenoid 42 is de-energized and the springs 28 thrust pistons 26 and brake shoes 27 against the sides of tool 14 with braking force. By applying the brake to the blade itself I prevent a possible throw off which might occur where a braking force is applied to the motor 10 or motor shaft 12 itself.
Having described a working embodiment of my invention, I claim:
1. In combination with a power-driven rotary cutting tool having an electric motor and cutting tool mounted on the armature shaft of said motor, a guard mounted on said motor and about a portion of said cutting tool, said guard having a cylinder positioned longitudinally parallel to the armature of said motor, a piston movable to and fro in said cylinder, a brake shoe secured on one end of said piston to engage said rotary cutting tool when said piston is moved to the forward end of said cylinder, resilient means to urge said piston to said forward end of said cylinder and into braking contact with said rotary tool, a solenoid mounted on said guard, a fulcrumed lever connecting said solenoid to said piston, said solenoid and said lever being operatively positioned to move said piston against said resilient member and out of braking position when said solenoid is energized and means connecting said solenoid across the terminals of said electric motor to energize said solenoid when said motor is energized whereby said braking means may be moved by said resilient means into braking position when said motor is de-energized and said braking means may be moved out of braking position when said motor is energized.
2. In a cutting mach ne having a motor and a rotary cutting tool, a bracket mounted about the edge of said cutting tool, a pair of oppositely positioned members mounted on said bracket movable to effect equal frictional engagement simultaneously on opposite sides of said cutting tool, resilient means on each of said members operative to move said members into frictional engagement with said cutting tool, a double acting solenoid positioned on said bracket beyond said tool and intermediate said members, and a pair of fulcrumed levers pivoted to said bracket and each engaged at its one end to one end of said double acting solenoid and at its other end to one of said movable members to move said members against said yielding means and out of frictional engagement with said cutting tool.
3. in a cutting machine having a motor and a rotary cutting tool, a bracket mounted about the edge of said cutting tool, a pair of oppositely positioned members mounted on said bracket movable to effect equal frictional engagement simultaneously on opposite sides of said cutting tool, resilient means on each of said members operative to move said members into frictional engagement with said cutting tool, a double acting solenoid positioned on said bracket beyond said tool and intermediate said members, a pair of fulcrumed levers pivoted to said bracket and each engaged at its one end to one end of said double acting solenoid and at its other end to one of said movable members to move said members against said yielding means and out of frictional engagement with said cutting tool, and an electrical conductor operatively connected to said solenoid and to said motor to energize said solenoid when said motor is in operation.
4. in a cutting machine having an electric motor and a rotary cutting tool, a bracket mounted about the edge or" said cutting tool, a pair of oppositely positioned members mounted on said bracket movable to effect equal frictional engagement simultaneously on opposite sides of said cutting tool, resilient means on each of said members operative to move said members into frictional engagement with said cutting tool, a double acting solenoid positioned on said bracket beyond said tool and intermediate said members, a pair of fulcrumed levers pivoted to said bracket and each engaged at its one end to one 5. The combination with a power driven rotary cutting tool having an electric motor and a source of elec:
tnic power, a guardmounted about a portion of said rotary tool, a brake shoe mounted on said guard on each side .of said tool movable from a tool engaging position to a non-engaging position, means to move said brake shoes into tool engaging position, a single electro-magnetic means to move said brake shoes out of tool engaging position, and single switch means operative when plosed to pant es; said, motor and said eleetrotnagnetic means to said source of power whereby said brake shoes are uniformly moved out of engaging position during the operation of said motor and uniformly released into braking position when said switch means is opened to stop said motor.
References Cited the tile of this patent UNITED STATES PATENTS 1,282,483 Steen Oct. 22, 1918 1,811,066 Tannewitz a y a June 23, 193 1 FQREIGN PATENTS 485,143 Germany Nov. 27, 1929
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US1168355 *||Feb 7, 1910||Jan 18, 1916||Alvey Ferguson Co||Electric bone-saw.|
|US1282483 *||Oct 2, 1916||Oct 22, 1918||Allis Chalmers Mfg Co||Compound band-brake.|
|US1811066 *||Feb 23, 1929||Jun 23, 1931||Tannewitz Carl E||Sawing machine|
|DE485143C *||Nov 27, 1929||Wilhelm Follender Grossfeld||Bremsbelagbefestigung|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US2801714 *||Jun 29, 1956||Aug 6, 1957||Meadville Res Products Corp||Heat insulating friction shoe and piston unit|
|US2960190 *||Feb 24, 1959||Nov 15, 1960||Molon Motor & Coil Corp||Motor brake|
|US2984268 *||Jul 7, 1958||May 16, 1961||Vuichard George E||Manually-actuated saw brake|
|US3103990 *||Nov 1, 1960||Sep 17, 1963||Faye M Pierson||Hydraulic disc brake|
|US3124219 *||Jan 3, 1961||Mar 10, 1964||Disc brake assembly|
|US3184003 *||May 15, 1961||May 18, 1965||Lambert & Brake Corp||Brake structure|
|US3322240 *||Mar 19, 1965||May 30, 1967||Mallory & Co Inc P R||Disc brake for washing machine|
|US3417843 *||Oct 26, 1966||Dec 24, 1968||Ingersoll Rand Canada||Disc brake for mine hoists|
|US3703654 *||Jun 30, 1971||Nov 21, 1972||Karubian Ralph||Hand tool with magnetic brake|
|US4145940 *||Jan 26, 1978||Mar 27, 1979||Woloveke Eugene L||Brake apparatus for a motor driven saw blade|
|US4315371 *||Jan 11, 1980||Feb 16, 1982||Asahi Seimitsu Kabushiki Kaisha||Preset brake device for line drawing machine, drafting machine or like|
|US4335514 *||Aug 8, 1980||Jun 22, 1982||Black & Decker Inc.||Switch-brake interlock for chain saw|
|US5253738 *||Jul 9, 1991||Oct 19, 1993||Inventio Ag||Safety disc brake for lifts|
|US6092448 *||Jan 21, 1999||Jul 25, 2000||Premark Feg L.L.C.||Slicer with staged dynamic braking system|
|US6813983||Jan 16, 2002||Nov 9, 2004||Sd3, Llc||Power saw with improved safety system|
|US6826988||Jan 16, 2002||Dec 7, 2004||Sd3, Llc||Miter saw with improved safety system|
|US6945148||Jan 14, 2002||Sep 20, 2005||Sd3, Llc||Miter saw with improved safety system|
|US6957601||Sep 17, 2001||Oct 25, 2005||Sd3, Llc||Translation stop for use in power equipment|
|US6994004||Jan 16, 2002||Feb 7, 2006||Sd3, Llc||Table saw with improved safety system|
|US7000514||Jul 25, 2002||Feb 21, 2006||Sd3, Llc||Safety systems for band saws|
|US7077039||Nov 12, 2002||Jul 18, 2006||Sd3, Llc||Detection system for power equipment|
|US7112018||Jan 19, 2005||Sep 26, 2006||The Boeing Company||Automatic position-locking tool carrier apparatus and method|
|US7197969||Sep 13, 2002||Apr 3, 2007||Sd3, Llc||Logic control with test mode for fast-acting safety system|
|US7231856||Jun 13, 2002||Jun 19, 2007||Sd3, Llc||Apparatus and method for detecting dangerous conditions in power equipment|
|US7290472 *||Sep 1, 2004||Nov 6, 2007||Sd3, Llc||Miter saw with improved safety system|
|US7350444 *||Aug 13, 2001||Apr 1, 2008||Sd3, Llc||Table saw with improved safety system|
|US7377199||Jan 16, 2002||May 27, 2008||Sd3, Llc||Contact detection system for power equipment|
|US7481140||Apr 15, 2005||Jan 27, 2009||Sd3, Llc||Detection systems for power equipment|
|US7610836||Aug 13, 2001||Nov 3, 2009||Sd3, Llc||Replaceable brake mechanism for power equipment|
|US7640837||Mar 27, 2008||Jan 5, 2010||Sd3, Llc||Table saw with improved safety system|
|US7644645||Nov 17, 2008||Jan 12, 2010||Sd3, Llc||Apparatus and method for detecting dangerous conditions in power equipment|
|US7661343||Apr 17, 2007||Feb 16, 2010||Sd3, Llc||Brake mechanism for power equipment|
|US7681479||Jun 4, 2007||Mar 23, 2010||Sd3, Llc||Motion detecting system for use in a safety system for power equipment|
|US7707920||Dec 31, 2004||May 4, 2010||Sd3, Llc||Table saws with safety systems|
|US7712403 *||Jul 2, 2002||May 11, 2010||Sd3, Llc||Actuators for use in fast-acting safety systems|
|US7784507||Aug 19, 2005||Aug 31, 2010||Sd3, Llc||Router with improved safety system|
|US7788999||Apr 10, 2006||Sep 7, 2010||Sd3, Llc||Brake mechanism for power equipment|
|US7827890||Jan 28, 2005||Nov 9, 2010||Sd3, Llc||Table saws with safety systems and systems to mount and index attachments|
|US7827893||Mar 14, 2007||Nov 9, 2010||Sd3, Llc||Elevation mechanism for table saws|
|US7832314||Jun 11, 2007||Nov 16, 2010||Sd3, Llc||Brake positioning system|
|US7836804||Dec 29, 2006||Nov 23, 2010||Sd3, Llc||Woodworking machines with overmolded arbors|
|US7866239||Mar 14, 2007||Jan 11, 2011||Sd3, Llc||Elevation mechanism for table saws|
|US7895927||May 19, 2010||Mar 1, 2011||Sd3, Llc||Power equipment with detection and reaction systems|
|US7908950||Jan 4, 2010||Mar 22, 2011||Sd3||Table saw with improved safety system|
|US7921754||Oct 9, 2009||Apr 12, 2011||Sd3, Llc||Logic control for fast-acting safety system|
|US7958806||Nov 2, 2009||Jun 14, 2011||Sd3, Llc||Replaceable brake mechanism for power equipment|
|US8011279||Dec 17, 2007||Sep 6, 2011||Sd3, Llc||Power equipment with systems to mitigate or prevent injury|
|US8061246 *||Mar 26, 2010||Nov 22, 2011||Sd3, Llc||Miter saw with improved safety system|
|US8430005 *||Nov 21, 2011||Apr 30, 2013||Sd3, Llc||Miter saw with improved safety system|
|US8490527||Sep 1, 2011||Jul 23, 2013||Sd3, Llc||Power equipment with systems to mitigate or prevent injury|
|US9038515||Aug 29, 2013||May 26, 2015||Sd3, Llc||Logic control for fast-acting safety system|
|US20020017184 *||Aug 13, 2001||Feb 14, 2002||Gass Stephen F.||Table saw with improved safety system|
|US20050204885 *||Sep 1, 2004||Sep 22, 2005||Gass Stephen F||Miter saw with improved safety system|
|US20120137848 *||Nov 21, 2011||Jun 7, 2012||Gass Stephen F||Miter saw with improved safety system|
|DE2952253A1 *||Dec 24, 1979||Jul 24, 1980||Asahi Seimitsu Kk||Voreinstellbare bremseinrichtung fuer eine zeichenmaschine|
|DE19750819A1 *||Nov 17, 1997||May 20, 1999||Kocks Technik||Tube and long stock cutting machine using powered disc tool|
|EP0042918A1 *||Apr 8, 1981||Jan 6, 1982||Robert Bosch Gmbh||Hand tool operated by an electric motor|
|EP0465831A1 *||Jun 6, 1991||Jan 15, 1992||Inventio Ag||Safety disc brake for elevators|
|U.S. Classification||83/68, 188/72.1, 188/59, 83/70, 188/110, 188/171|
|International Classification||F16D55/224, B27B5/38, F16D59/02, F16D65/14|
|Cooperative Classification||F16D59/02, F16D55/2245, F16D2121/22, B27B5/38|
|European Classification||F16D59/02, B27B5/38, F16D55/224B|