VARIABLE-RATIO TORIC DRIVE WITH HYDRAULIC RELIEF MEANS

• US 3,802,284 A
• Filed: 08/02/1972
• Issued: 04/09/1974
• Est. Priority Date: 08/02/1972
• Status: Expired due to Term

• Current Assignee: James Christopher Herbert Triffiti, Raymond Sharpe
• Original Assignee: James Christopher Herbert Triffiti, Raymond Sharpe
• Inventors: Triffiti, James Christopher Herbert, Sharpe, Raymond
• Primary Examiner(s): Wyche, Benjamin W.
• Assistant Examiner(s): Burke, Allan Russell
• Application Number:
  US05/277,253
• Time in Patent Office: 615 Days
• Field of Search: 74/190,200,208 91/402
• US Class Current: 476/10
• CPC Class Codes: F16H 15/38 with two members B having hollow toroid surfaces opposite to each other, the member or members A being adjustably mounted between the surfaces
• CPC Class Codes: F16H 2015/383 with two or more sets of toroid gearings arranged in parallel

Abstract

A variable-ratio frictional drive gear comprises at least two axially spaced torus discs between which there is a set of circumferentially spaced drive rollers in frictional rolling contact with toroidal surfaces on the discs. Each roller is rotatably mounted in a tangentially controlled roller carriage having end portions lying on a roller tilt axis at right angles to the axis of rotation of the roller. The end portions of each roller carriage are slidably and rotatably supported by a support member whereby the roller carriages can be moved tangentially in order to control indirectly the ratio angle of the roller. There is further provided a piston which is slidable in the cylinder and which is connected to one end portion of a carriage of at least one roller to thereby, in use, effect tangential movement of the roller carriage. Means are also provided to reduce fluid pressure which, in use, is applied to the piston, such reduction occurring when the piston reaches a predetermined axial position.

Claims

1. A gear comprising at least two axially spaced torus discs between which there is a set of circumferentially spaced drive rollers in frictional rolling contact with toroidal surfaces on the discs, the rollers being rotatably mounted in respective tangentially controlled roller carriages having end portions lying on roller tilt axes at right angles to the axes of rotation of the respective rollers, the end portions of the roller carriages being slidably and rotatably supported by a support member whereby the roller carriages can be moved tangentially in order indirectly to control the ratio angle of the rollers, and piston means slidable in a cylinder to which fluid under pressure is applied in use, said piston means being connected to one end portion of at least one roller carriage to effect tangential movement of the roller carriage, means being also provided to reduce said fluid pressure, such means being operable to reduce said pressure when the piston reaches a predetermined axial position.

2. A gear As claimed in claim 1 wherein said means comprises at least one recess formed in said piston means so positioned that when said piston means reaches said predetermined axial position, fluid can escape from said cylinder through said recess.

3. A gear as claimed in claim 2 wherein end portions of the roller carriages are universally connected to respective individual piston means which are in the form of pistons slidable in respective cylinders arranged with their axes normal to the disc axis.

4. A gear as claimed in claim 2 wherein only one piston means having said recess is provided, said one piston means being connected to an end portion of one roller carriage to effect movement thereof, the remaining roller carriages each having end portions thereof connected to respective pistons slidable in cylinders under the influence of fluid emanating from a supply of such fluid to said one piston means.

5. A gear as claimed in claim 4 wherein said piston means is in the form of a spool valve having a recess in the form of an annular groove which defines, together with the body of the valve, an annular passage, the annular passage and one axial end of the spool valve being connected to a supply of fluid, the annular passage being arranged to communicate with an outlet in said valve body when the spool adopts a predetermined position relative to said valve body.