GB2062432A - Rotary cultivating machine - Google Patents

Abstract

A rotary cultivating machine is mounted behind a tractor and is driven by the tractor power take off. To enable the machine to be driven at relatively high power take off speeds and transmit greater torque to the rotor shaft carrying the cultivating tools, step-down gearing is located at the driven end of the rotor shaft. The machine has a gearbox 17 for connection to the power take off shaft. An output shaft from the gearbox is connected to a side drive arrangement 25 and the side drive arrangement drives the rotor shaft through the step-down gearbox 30, preferably in the form of an epicyclic gearbox. <IMAGE>

Description

SPECIFICATION Rotary cultivating machine This invention relates to rotary cultivating machines and in particular to such machines as have a rotor shaft on which cultivating tools are mounted, the shaft extending generally horizontally and transverse to the direction of travel over the ground.

Tractor-mounted rotary cultivating machines usually are driven from the powertake-off shaft of the tractor through transmission means which includes a gearbox with change speed means for changing the drive ratio, and gear wheels or sprockets by which the drive is transmitted from the gearbox to the rotor carrying the cultivating tools. The rotor is generally driven within a certain speed range which is varied according to the nature of the cultivating operation by the change speed means. The tractor power take-off is usually operable attwo speeds, 540 and 1,000 rpm, and some rotary cultivating machines can be operated with the powertake-off at either one of these speeds but in this case the change speed means is used to reduce the rotor speed at the higher input speed.Given the need to retain the rotor speed within a limited range of, say 150 (or less) to 270 rpm the speed reduction from the powertake-offtothe rotor has hitherto been achieved in the gearbox and, to a lesser extent, in the sprockets or gears transmitting drive from the gearbox to the rotor shaft. Thus the transmission means, at least downstream of the gearbox, runs at a speed approaching that 6f the rotor shaft.

One object of the invention is to provide a rotary cultivating machine in which the transmission means can be run at a relatively high speed so as to transmit more torque to the rotor.

According to the invention a rotary cultivating machine comprises a mobile frame, a transversely and horizontally extending rotor shaft mounted on the frame and carrying cultivating tools, and drive transmission means for transmitting drive to the rotor shaft, the drive transmission means including a gearbox mounted on the frame, arranged for releasable connection to driving means and having an output shaft, a side drive arrangement mounted on an end of the frame for transmitting drive from the output shaft towards the rotor shaft, and step-down gearing interposed between the side drive arrangement and the rotor shaft whereby drive is transmitted to the rotor shaft so that the gearbox output shaft and the side drive arrangement are run at relatively high speed compared with the rotor shaft speed.

Preferably the step-down gearing is in the form of an epicyclic gearbox.

By the use of step-down gearing interposed between the transmission means and the rotor shaft the torque transmitted to the rotor shaft can be considerably increased compared with machines using a similar transmission means merely by increasing the speed of the drive at the input end of the transmission means compared with such known machines.

Further features of the invention appear from the following description of an embodiment of the invention given by way of example only and with reference to the drawings, in which: Figure lisa rear elevation of part of a rotary cut- tivating machine, Figure 2 is a view from one end of the machine of Figure 1, and Figure 3 is a section on the line 3-3 in Figure 1.

Referring to the drawings a rotary cultivating machine is shown which is in several respects of known form. The machine is mounted on the three point linkage of a tractor (not shown) and comprises a frame 10, only the central portion and one end of which is shown. The frame 10 includes a horizontal and transverse member 11 which has longitudinal bars 12 and an upper shield member 13 and at the ends of the member 11 are side frame members 14 (only one of which is shown) which are supported by the transverse member 11 and extend downwardly to support a transverse and horizontal rotor shaft 15, the direction of travel of the machine being shown by arrow A in Figure 2.

The transverse member 11 supports part of the drive transmission means for the rotor comprising a gearbox 17 having an input shaft 18 arranged for releasable connection to the tractor powertake-off shaft 21 (only part of which is shown). In known manner the gearbox 17 includes change speed means for changing the drive ratio which means in this case is in the form of interengaging pick-off gears 19 and 20 which can be replaced by other gears having different numbers of teeth so as to change the drive ratio.

The pick-off gears 19 and 20 transmit drive from the gearbox through bevel gears 22 and 23 to an output shaft in the form of a transverse jackshaft located in a tube 24 which extends to one side of the machine to a side drive arrangement 25. The side drive 25 includes a sprocket 26 drivingly connected to the end of the jackshaft and a drive chain 27 extends around the sprocket 25 to drive a further sprocket 28 which is co-axial with the rotor shaft 15.

If preferred the side drive arrangement may take the form of a set of gear wheels whereby drive is transmitted from the jackshaft.

It will be appreciated that the non-illustrated side frame member at the other end of the machine to the frame member 14 rotatably supports the other end of the rotorshaft 15 and isof known form.

As thus far described the machine may be of known form with components, particularly in the transmission means, which do not need to differ substantially in form or dimensions from known rotary cultivating machines. However, as distinct from such known machines in which the sprocket 28 drives the shaft 15 directly, the drive from the sprocket 28 to the shaft 15 is through step-down gearing, in the illustrated form constituted by an epicyclic gearbox 30 (seen more clearly in Figure 3).

Drive from the sprocket 28 is transmitted through a splined connection 31 to a hub 32 in which is received a stub shaft 33 drivingly connected to the hub 32 by splines 34 at one end of the shaft 33. At the other end of the shaft 33 is a gear or sun wheel 35 which engages with planet wheels 37 mounted on spindles 38. The spindles 38 are located in radial arms 39 rotatable with a further stub shaft 40. An annular member 42 is drivingly connected to the stub shaft 40 and is formed with a radial flange 43 having bolt holes 44 whereby the flange 43 is connected to a flange 64 carried on one end of the rotor shaft 15 and provided with co-operating holes 65.

The flange 64 has further holes 66 for locating cultivating tools 71 in the usual manner. If the tools are of L-shaped form, as shown, the transverse limb of the L extends towards the side frame 14 to cultivate the ground under the epicyclic gearbox 30.

The gearing 30 also includes an annulus 67 mounted on bearings 68 at one end which cooperate with the exterior of the hub 32, and on bearings 69 at the other end which co-operate with the stub shaft 40 which is also sealed by seals 70. Inter wally the annulus 67 has circumferential teeth 72 which engage with the planet wheels 37. The annulus 67 is attached to the lower end of the side member 14 by bolts (not shown) which pass through holes 73 in the side member 14 and bores 74 in the annulus 67.

It will be seen that drive to the epicyclic gearbox 30 from the sprocket 28 is through the hub 32 to the shaft 33. Rotation of the shaft 33 causes the planet wheels 37 to rotate about the axes of their spindles 38 while the annulus 67 remains stationary. Rotation of the planet wheels 37 causes the stub shaft 40 to rotate about its axis at a relatively slower speed than the sprocket 28to thereby effect a speed reduction between the sprocket and the rotor shaft 15 driven by the stub shaft 40.

The rotor shaft 15 carries spaced flanges 75 on which cultivating tools 71 are carried.

As an example of the use of the invention the machine may be driven by a powertake-offshaft 21 running at 1000 rpm to give a jackshaft speed of between 500 and 1500 rpm, depending on the gears 19,20 which are fitted in the gearbox 17. The sprockets 26,28 may provide a 1:1 ratio and the epicyclic gearbox 30 arranged to give the desired speed reduction sothatthe rotor shaft 15 can be driven at between 100 and 300 rpm which is in the range of rotor shaft speeds normally required.It will be seen, therefore, that the machine is able to transmit increased torque to the rotor shaft using conventional transmission means running at relatively higher speeds than hitherto by the interposition of the reduction gearing immediately before the rotor shaft, so enabling greater torque to be transmitted to the rotor shaft than hitherto on machines using equivalent transmission components.

Instead of the rotor shaft being coaxial with the epicyclic gearing, the shaft may be displaced from the central axis of the reduction gearing by, for example, interposing further gears.

Instead of the epicyclic gearing described it will be appreciated that other reduction gearing can be employed. For example a ring gear may be used by mounting a small gearwheel on the rotor shaft which engages the internal teeth formed on the relatively large diameter ring gear wheel, the ring gear being driven by the sprocket mounted on the lower end of the side frame. By this means a similar reduction ratio to the epicyclic gearing can be achieved.

Claims (6)

1. A rotary cultivating machine comprising a mobile frame, a transversely and horizontally extending rotor shaft mounted on the frame and carrying cultivating tools, and drive transmission means for transmitting drive to the rotor shaft, the drive transmission means including a gearbox mounted on the frame, arranged for releasable connection to driving means and having an output shaft, a side drive arrangement mounted on an end of the frame for transmitting drive from the output shaft towards the rotor shaft, and step-down gearing interposed between the side drive arrangement and the rotor shaft whereby drive is transmitted to the rotor shaft so that the gearbox output shaft and the side drive arrangement are run at relatively high speed compared with the rotor shaft speed.

2. A rotary cultivating machine according to Claim 1 wherein the step-down gearing is an epicyclic gearbox including a sun wheel which is drivingly connected to the side drive arrangement, a fixed annulus located around the sun wheel, and a planet wheel engaging with the sun wheel and the annulus and in driving connection with the rotor shaft.

3. A rotary cultivating machine according to Claim 2 wherein the side drive arrangement includes a pair of sprockets drivingly connected to one another by a chain, one of the sprockets being drivingly connected to the gearbox output shaft and the other sprocket being drivingly connected to the sun wheel of the epicyclic gearbox.

4. A rotary cultivating machine according to any one of the preceding claims wherein the step-down gearbox is drivingly connected to the rotor shaft through an outwardly directed flange mounted on the shaft and carrying a cultivating tool arranged to cultivate the ground underthe step-down gearbox.

5. A rotary cultivating machine according to any one of the preceding claims wherein the drive ratio of the transmission means is such that with the driving means operating at 1000 rpm and the output shaft from the gearbox rotating at 500 to 1500 rpm, the rotor shaft operates at between 100 and 300 rpm.

6. A rotary cultivating machine substantially as described with reference to the drawings.