AU629474B2 - Transmission system - Google Patents

Description

629474COMMONWEALTH OF AUSTRALIA COMMONWEALTH OF AUSTRZALIA Patents Act 1952 0 00 000 0000 o o O 0 o0oo 0 C '00 0 0 o o 0 0 0 0 0 0 P 0 00 o o Name of Applicant NEVILLE ROY DORNE Address of Applicant: 78 Elizabeth Street, Urangan, Queensland, 4655, Australia Actual Inventor NEVILLE ROY DORNE Address for Service GRANT ADAMS COMPANY, Patent Trade Mark Attorneys, Level 9, National Mutual Centre, 144 Edward Street, BRISBANE. QLD. 4000

AUSTRALIA.

0 a o o o0 a 0 e COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: "TRANSMISSION SYSTEM" The following statement is a full description of the invention including the best method of performing it known to the applicant.

THIS INVENTION relates to a transmission system, in particular to a transmission system suited to connecting a source of motive power to the drive wheels of vehicles such as ride on mowers.

Prior Australian Patent Application No.

72572/81 to Reinhold sets out a form of transmission system that is widely used in the production of motor mowers. Typically, this assembly provides no difference in drive ratio in forward and reverse, resulting in forward or reverse to be selected with the same speed.

It is disadvantageous f)r reverse to be selected this way with no control over speed. Ride-on mowers are the cause of many accidents and the transmission system is a oaoo factor in some of the accidents.

15 It is an object of the invention to provide a transmission system which can be utilised in a vehicle oo such as a motor mower which system enables the forward o o and reverse speed of travel to be different.

Various advantages of the invention will hereinafter become apparent.

The invention achieves its object by provision o of a vehicle trenismission system comprising: a coupling to a source of motive power; .0 ~a pair of contra-rotating driven pulleys powered by the source of motive power via the coupling; a clutch mechanism associated with each pulley to transfer power to an associated one of two drive means; the two drive means are separately coupled 30 to an output shaft each with different ratios; and the output ratio being selected with the actioning of either one or the other of the clutch mechanisms.

A transmission system of the above form might be applied to a range of vehicle types, motor mowers, golf buggies, etc, and its application in any particular circumstance will determine various factors such as output speeds, and other like matters of engineering design which will be obvious to a man skilled in the art.

The invention will now be described with reference to the drawings in which: FIG. 1 is a detailed sectional view of a clutch assembly which may be utilised in a transmission system in accordance with the invention; FIG. 2 illustrates how the clutch assembly of figure 1 is built into a transmission system in accordance with the invention; and °ooo FIG. 3 is a perspective view of an embodiment 15 of the invention.

0 In FIG. 1, a shaft 10 supports a sleeve 11 Swhich is axially movable thereon. Upon sleeve 11 are supported clutch plates 12 and 13, each being rotatable about sleeve 11. Each clutch plate 12 and 13 is integral with a respective sprocket at 14 and 15. Also supported on shaft 10 are two pulleys 16 and 17 providing surfaces on which are mounted clutch pads 18 0 Q and 19 to be engaged by clutch plates 12 and 13 when o sleeve 11 is moved in the manner described below.

In operation of the assembly of FIG. 1, the two pulleys 16 and 17 are engaged by a belt thereabout which extends about upper and lower pulleys (not shown) in reaches out of the plane of the drawing as is usual with these arrangements, and as shown in the aforementioned Reinhold specification, such that the two pulleys 16 and 17 are linked to rotate oppositely on shaft 10. The sleeve 11 has a channel 20, between flanges 21 and 22 thereabout, in which a select mechanism can be engaged to push sleeve 11ii to the left or right on shaft 10. By this means, sleeve 11 brings

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either of clutch plate 12 or 13 into engagement with pulley 16 or 17 respectively to cause either one of the sprockets at 14 or 15 to turn with its respective pulley. The direction of rotation of the two sprockets at 14 or 15 is opposite to each other and which one is selected for rotation depends on the position of sleeve 11. Rotation of sprockets 14 and 15 is determined by movement of the sleeve 11.

FIG. 2 shows a more complete overview of a transmission system incorporating the assembly of figure 1 with shaft 10 mounted between side frames 26 and 27.

The sleeve 11 is moved to the left or the right by the o lever arm 23 pivoted at 24 with its end in channel 20 in '000 ooo sleeve 11. Movement of the sleeve engages forward or S 15 reverse, as described above, with either of sprockets 14 and 15 being operatively coupled with belt 33 about u0o0 o pulleys 16, 17, 25 and a further pulley not shown, as is 0 usual with this type of transmission. Each of sprockets 14 and 15 may be connected to sprockets 30 and 31 respectively by suitable chains 40 and 41 to cause the final dr 4 .ve sprocket 28 on lay shaft 29, which carries sprockets 28,20 and 31, to rotate clockwise or Scounterclockwise, to establish either a forward or reverse drive. In practice power may be input at the belt 33 and transmitted to an output chain at the sprocket 28 with a preset ratio set by the choice of sprockets 14, 15, 30 and 31.

Returning to FIG. i, the clutch plates 12 and 13 may be integral with sleeves 34 and 35 respectively, which plates are mounted to sleeve 11 by bearings 36 and 37 to permit rotation on sleeve 11. The pulleys 16 and 17 are mounted to shaft 10 on bearings 38 and 39 respectively to permit their rotation. The shaft between bearing abutments 52 and 53 may be round such that sleeve 11, which may be a complementary sliding q fit, does not suffer the disadvantage of prior art square section arrangements.

In the above mentioned Reinhold specification the following is stated to be a disadvantage of prior apparatus. The clutch plate assembly is normally cast in one or two pieces with a square aperture being formed centrally. In this arrangement the square aperture in the clutch assembly cannot always be accurately formed in a casting process. As a result the clutch assembly cannot be consistently made to a close sliding fit on the driven shaft so that in many instances the clutch tends to rattle and in some instances it may even lock 0o up on the shaft.

^oo In the herein described apparatus, an advantage of the sleeve (11) sliding on the shaft is that since they may be both of a round form they are easier to machine to acceptable tolerances to give a °o good sliding fit compared to prior square sections.

FIG. 3 is a perspective view of a section of a vehicle in accordance with the invention. The vehicle Sis supported on a wheeled chassis 42. The wheels are a o 6 not shown. The mounting of wheels is within the competence of a man skilled in the art and any of the standard techniques might be employed. In the chassis, there is provided a sub-carrier 43 which rests upon chassis 42 on lugs such as 44 and fixed thereto by bolts such as bolt 45 through lugs such as lug 44 and chassis 42. By this means a transmission unit in accordance with the invention can be supported as a unit on the 30 sub-carrier to be removed simply by the breaking of r chains, disconnection of belts, the unbolting of the sub-carrier 43, etc.

The chains 40 and 41 of FIG. 2 about the sprockets 30 and 31 on lay shaft 29 in FIG. 2 may be tensioned by the means shown in FIG. 3 wherein lay shaft 29 is received at each end in a bearing in a bearing block (bearing block 48 is in view) which block is bolted at the top to a support plate such as plate 47 by bolt 49 (the same structure is repeated at the other end of the lay shaft 29). The bearing block 48 is bolted at the bottom of plate 47 as is seen in plate 46 at the opposite side of chassis 42. Plate 46 is provided with a slot 50 through which bolt 51 passes to bolt the bearing block at this end to plate 46. By loosening the bolts, the position of the lay shaft may be varied by rotation of the bearing blocks through the arc of the slots such as 50 in plate 46.

o 0 0 In FIG. 3, the forward and reverse yoke 23 is provided with opposed centering springs such as 54 each 15 with an adjusting nut 25. The drive wheels may be cD0O provided with a disc brake and action of the brake can oobo o be by pedal action which simultaneously decouples the -o clutch mechanism, the yoke 23 being centred at a neutral position. Drive wheels are mounted by any standard technique to the frame 42. A steering mechanism, motor, and operator seat and controls are likewise mounted to o this frame.

DBy adopting the above structure, a motor mower, or other like vehicle, is readily provided with a qvQ lower speed in reverse than forwardly.

Whilst the invention is described above with regard to certain specific features, it will be clear othat a man skilled in the art might make substantial variations therefrom that are within the scope of the following claims. Where sprockets and chains or pulleys and belts are utilised, clearly other couplings might be used with gear trains, belt drives, chain drives, etc.

being applicable as alternate means for the respective couplings, their substitution comprising simple engineering. The invention is aimed generally at low speed vehicles such as ride-on motor mowers, golf buggies, etc. and the usual simplified constructions of these vehicles can be adopted. However, other additional features, differentials, brake pads at all wheels, for example, are readily added to the above described vehicle in the standard manners for their utilisation.

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Claims (9)

1. A vehicle transmission system comprising: a coupling to a source of motive power; a pair of contra-rotating driven pulleys powered by the source of motive power via the coupling; a clutcrn mechanism associated with each pulley to transfer power to an associated one of two drive means; the two drive means are separately coupled to an output shaft each with different ratios; and the output ratio being selected with the actioning of either one or the other of the clutch o mechanisms. ooo

2. A vehicle transmission system as claimed in c Claim 1 wherein: the output shaft is fitted with a pair of op wheels by which the vehicle is propelled, the output .0. shaft being coupled to a lay shaft, the lay shaft being i oo coupled to each of the two drive means with different transfer ratios. o

3. A vehicle transmission system as claimed in Claim 2 wherein: B 0 am the drive reans are coupled to the lay shaft o °0 by chains spanned therebetween :.out sprockets whose size set the different transfer ratios, the lay shaft being supported between two spaced pivoted plates whose angle about the pivot is adjustable, the plates being locked at a selected position to adjust tension in the chains. 30

4. A vehicle transmission system as claimed in any one of Claims 1 to 3 wherein: B'>'0 each clutch mechanism comprises a clutch plate mounted co-axially with its respective pulley and axially movable relative thereto, the two clutch plates being mounted at a fixed spaced distance apart as an I I -T- axially movable unit whose movement one way or the other engages one clutch plate with its respective pulley, each clutch plate being integrally associated with a sprocket by which power is transmitted to the associated drive means.

A vehicle transmission system as claimed in Claim 4 wherein: each clutch plate is rotatively mounted to a sleeve which is mounted to a shaft and axially movable therealong, the respective pulleys being rotatively supported by the sl3ceve.

6. A vehicle transmission system as claimed in o Claim 5 wherein: eacn pulley is provided with a concentric annular clutch pad which engages against a complementary flat face of its respective clutch plate o to effect a clutch action, the associated sprocket being mounted integral.ly with the clutch plate on an axial sleeve projected therefrom oppciitely to the clutch pad.

7. A vehicle including a transmission system as claimed in any one of the preceding claims wherein: the vehicle comprises a chassis and a 00 detachable sub-carrier, the detachable sub-carrier having mounted thereon the transmission system.

8. A vehicle as claimed in Claim 7 wherein. the sub-carrier is rectangular and is nested within a complementary rectangular space within the chassis from above, nested thereon on lugs projected off the sub-carrier, the sub-carrier being bolted to the chassis by bolts passed through the lugs.

9. A vehicle as claimed in Claim 8 wherein: driven wheels powered by the transmission system are provided on an axle carrying a sprocket which the transmission system couples via a chain drive, the axle being fitted with a disc brake whose operation I L ~q~prreourr~- is effected in tandem with a decoupling of the clutch mechanism. A vehicle transmission substantially as hereinbefore described with reference to the accompanying drawings. DATED this twenty-sixth day of April 1991. NEVILLE ROY DORNE, by his Patent Attorneys, GRANT ADAMS COMPANY. o 0 0 ABSTRACT A transmission providing different ratios in forward and reverse. Power to a drive shaft is passed under action of a clutch mechanism to either of a forward or reverse drive train. The drive trains can be coupled to a common lay shaft which is coupled to the drive shaft. Power is continuously apilied to two contra-rotating clutch pads. The clutch mechanism comprises two clutch plates moved into alternate engagement with one or the other clutch pads. Different ratio sprockets may be associated with the clutch a plates, each of a forward and reverse sprocket being may be connected by a drive chain to the lay shaft. c 0 t