Patents by Inventor David T. Allan

David T. Allan has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5095600
    Abstract: There is described a paving breaker wherein vibrational forces arising from reciprocation of the breaker are reduced at the breaker handles by removing the conventional direct attachment of the handles to the breaker, and instead resiliently coupling the handles to the working bit. There is also described a support for a paving breaker said support having a powered lift provided with at least one ground engageable wheel. The powered lift is under the control of a manually operable control mounted in the support.
    Type: Grant
    Filed: April 2, 1990
    Date of Patent: March 17, 1992
    Inventor: David T. Allan
  • Patent number: 4997050
    Abstract: A scabbler bit comprises a carrier having a body 30 with a lower face 31 formed to provide bores 32 for receipt of scabbler tips 44. The body 30 has a central bore 33 for passage of a fixing shank 34. The bore 33 is enlarged at the lower face 31 to form a recess 35 to receive the head 36 of the shank 34. The opposite face of the body 30 is formed with a counterbore 37 to receive the piston 38, the shank 34 being retained in the piston by a pin 39. Thus, axial loads on the scabbler bit are transmitted to the piston 38 via shoulder 40 of the carrier bearing on end face 41 of the piston 38, while any sideways of twisting load is resisted by the wall of the counterbore 37 bearing on the side face 42 of the piston 38.
    Type: Grant
    Filed: December 21, 1989
    Date of Patent: March 5, 1991
    Assignee: John MacDonald and Company (Pneumatic Tools) Limited
    Inventor: David T. Allan
  • Patent number: 4841842
    Abstract: There is described apparatus for scabbling concretw which includes a hollow cylinder block having a top and bottom plate between which plates there is provided a smooth sided hollow cylindrical cylinder liner. The piston for reciprocation within the cylinder liner is also provided.
    Type: Grant
    Filed: September 5, 1986
    Date of Patent: June 27, 1989
    Assignee: John MacDonald & (Pneumatic Tools) Ltd.
    Inventor: David T. Allan
  • Patent number: 4534421
    Abstract: A tool assembly in which the tool holder 6 forms a relatively small volume of metal thereby facilitating brazing of the tool bits (21, 23) and inexpensive replacement.
    Type: Grant
    Filed: August 5, 1982
    Date of Patent: August 13, 1985
    Inventor: David T. Allan
  • Patent number: 4526190
    Abstract: A control valve assembly for a pneumatic paving breaker which enables the maximum amount of energy to be imparted to the piston on its working stoke while restricting the energy imparted to the piston on its return stroke and which utilizes a reduced consumption of air, has an optimum speed of response and is relatively cheap to manufacture. This is achieved by having a valve member in the form of a pure cylindrical slug which reciprocates in a valve block in which it is a clearance fit.
    Type: Grant
    Filed: August 9, 1983
    Date of Patent: July 2, 1985
    Inventor: David T. Allan
  • Patent number: 4502734
    Abstract: There is provided an improved scabbler bit wherein the bit is fixable to a piston of a scabbling machine through a male shank portion. The shank portion carries a circumferential groove for cooperation in the side wall of the piston to hold the shank firmly within the piston. There is also provided a scabbler bit wherein the shank portion is separate from the carrier. A novel design of a scabbler tip is also disclosed together with a novel arrangement of tips on the base of a tip carrier.
    Type: Grant
    Filed: June 23, 1982
    Date of Patent: March 5, 1985
    Inventor: David T. Allan
  • Patent number: 4225187
    Abstract: A scabbler machine for breaking concrete etc. having a number of scabbling bits made up of a shank for connection to the reciprocal piston of the scabbler machine and a head provided with tungsten carbide, or like, cutting members. To ensure complete scabbling of the surface to be treated the head of the scabbling bits have portions which overlie portions of other bits so that the bits overlap one another in the direction of movement of the scabbler machine over the surface to be treated.
    Type: Grant
    Filed: August 4, 1978
    Date of Patent: September 30, 1980
    Assignees: David Thomson Allan, John MacDonald & Co. (Pneumatic Tools) Ltd.
    Inventor: David T. Allan
  • Patent number: 4186810
    Abstract: An undercutter comprising a slotted tubular body in which is mounted an extendable and retractable cutting head for undercutting a bore into which the tubular body is positioned and rotated. The cutting head includes a fluid-operated reciprocally movable piston, the reciprocating rate of which is determined by an annular liner positioned between the outer wall of the piston body and the inner wall of the piston cavity.
    Type: Grant
    Filed: July 5, 1977
    Date of Patent: February 5, 1980
    Assignees: John MacDonald & Company (Pneumatic Tools) Limited, David Thomson Allan
    Inventor: David T. Allan
  • Patent number: 4153121
    Abstract: The invention herein relates to an undercutting device which is provided with a substantially tubular body adapted to be placed within a parallel-sided hole. A rotary percussion head is provided at one end of the body and has one or more cutting tools which extend radially therefrom at an obtuse angle and which cutting tools are adapted to cut outwardly from the radius of the body, means are provided for rotating the head about the axis of the body and for operating the percussion head at one predetermined depth in the hole so that the cutting tools may act on the wall of the parallel-sided hole.
    Type: Grant
    Filed: December 13, 1976
    Date of Patent: May 8, 1979
    Assignee: John MacDonald & Company (Pneumatic Tools) Ltd.
    Inventor: David T. Allan
  • Patent number: 4140347
    Abstract: A hand-held groove cutter, particularly for cutting grooves in concrete structures, comprises a movable carriage having wheels for rolling over the concrete structure, and a fluid-operated percussion hammer mounted on the carrier. The hammer includes a piston and a cylinder which is mounted for sliding movement in a housing, and a tool which is connected to the piston. An adjustment arrangement is operative for moving the cylinder relative to the housing to thereby adjust the stroke of the piston and the depth of stroke of the tool.
    Type: Grant
    Filed: January 19, 1977
    Date of Patent: February 20, 1979
    Assignees: John MacDonald & Co. (Pneumatic Tools) Ltd., David Thomson Allan
    Inventor: David T. Allan