AU734026B2

AU734026B2 - Counter-Rotating Marine Gearbox

Info

Publication number: AU734026B2
Application number: AU57370/98A
Authority: AU
Inventors: Murray Charles Coxall
Original assignee: Coxall Anne Elizabeth; Coxall Kay Frances
Current assignee: Coxall Anne Elizabeth; Coxall Kay Frances
Priority date: 1997-03-12
Filing date: 1998-03-06
Publication date: 2001-05-31
Anticipated expiration: 2018-03-06
Also published as: AU5737098A

Description

C.i P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant: Actual Inventor: Address for service in Australia: Invention Title: Murray Charles COXALL Murray Charles COXALL Freehills Carter Smith Beadle 101 Collins Street Melbourne Victoria 3000 Australia COUNTER-ROTATING MARINE GEARBOX Details ofAssociated Provisional Application: P05568 filed 12 March 1997 The following statement is a full description of this invention, including the best method of performing it known to us DVG:JMD:40476444 26 February 2001 COUNTER-ROTATING MARINE GEARBOX Technical Field of the Invention This invention relates to improved gearboxes for marine application.

Background to the Invention For many people the lack of drive smoothness under acceleration caused by high torque conditions which leads to stability of the craft using a single drive, can cause uneasiness and indeed compromises safety.

This problem has been alleviated to a certain extent by using two drives.

This can be achieved by using two engines or by twin counter-rotating screws or propellers driven by the one engine. These twin screws are usually co-axially located. Examples of such co-axial arrangements are US Patents 5,230,644, 6,053,782 and 5,791,950. Australian patent application 77656/75 discloses a marine drive system with laterally spaced drive shafts rather than co-axial shafts.

However, the invention of 77657/65 requires the inclusion of universal joints which adds to the complexity of the drive arrangements.

Summary of the Invention This invention provides in one form a marine gearbox with counter-rotating laterally spaced output shafts, the gearbox comprising a single input shaft adapted V 20 to be rotated in either direction, a first gear located on the input shaft, a second gear adapted to mesh with the first gear, the second gear being fixed on a second shaft, a third gear fixed on the second shaft and adapted to mesh with a fourth gear fixed on a first output shaft, a fifth gear fixed on an idler shaft located on the opposite side of •oothe input shaft to the first shaft and wherein the fifth gear is adapted to mesh on a 25 sixth gear fixed on a second output shaft as well as to mesh with said third gear.

~Preferably the marine gearbox includes a dog clutch arrangement on the input shaft.

Preferably the output shafts are splayed at an angle of up to 0 Preferably first and second gears are interchangeable enabling the speed of rotation of the output shafts to be changed.

DVG:JMD:40476444 29 March 2001 Detailed Description of the Invention The invention will be further described by reference to a preferred embodiment illustrated in the drawings.

Figure 1 is a sectional plan view of a marine gearbox according to the present invention.

Referring to Figure 1 the marine gearbox 1 has a housing 2. An input shaft 3 is located in the centre of the gearbox 1 by roller bearings 4, 5. The input shaft 3 can be driven by an engine (not shown) from either end via a flange or splined coupling keyed to the input shaft 3. A dog clutch 6 is shown on the input shaft 3.

The input shaft 3 has a first gear 7 which meshes with a second gear 8 fixed on a second shaft 9. This second shaft 9 is supported by bearings 10, 11. A third gear 12 is located on the second shaft 9. This third gear 12 meshes with a fourth gear 13 fixed to a first output shaft 14 mounted in bearings 15, 16. The output shaft 14 is splayed by 40 from the input shaft 9. The third gear 12 also meshes with a fifth gear 15 17 located on an idler shaft 18 supported by bearings 19, 20. The fifth gear 17 *o o.

meshes with a sixth gear 21 fixed on the second output shaft 22. The second output shaft 22 is supported by bearings 23, 24. The second out put shaft 22 is also splayed by 40 from the input shaft 3. The two output shafts are splayed relative to i each other by a total of 80. In operation rotation of input shaft 3 causes output 20 shafts 14, 22 to counter-rotate. The output shafts are shown laterally spaced and splayed. The angle of splaying between the output shafts may be up to 8'.

oooo *o go DVG:JMD:40476444 26 February 2001

Claims

1. A marine gearbox with counter-rotating laterally spaced output shafts, the gearbox comprising a single input shaft adapted to be rotated in either direction, a first gear located on the input shaft, a second gear adapted to mesh with the first gear, the second gear being fixed on a second shaft, a third gear fixed on the second shaft and is adapted to mesh with a fourth gear fixed on a first output shaft, a fifth gear is fixed on an idler shaft located on the opposite side of the input shaft to the first shaft and wherein the fifth gear is adapted to mesh on a sixth gear fixed on a second output shaft as well as to mesh with said third gear.

2. A marine gearbox as defined in claim 1 wherein the marine gearbox includes a dog clutch arrangement on the input shaft.

3. A marine gearbox as defined in claim 1 or claim 2 wherein the output shafts are splayed at an angle of up to

4. A marine gearbox as defined in any one of claims 1 to 3 wherein the first and second gears are interchangeable to enable the speed of rotation of the output shafts o 20 to be changed.

5. A marine gearbox substantially as hereinbefore described with reference to the drawings. ooooo 29 March 2001 FREEHILLS CARTER SMITH BEADLE Patent Attorneys for the Applicant: 'Murray Charles COXALL DVG:JMD:40476444 29 March 2001