Transmission unit

Claim 2

A transmission unit having an input shaft, an output shaft in co-axial alignment with the input shaft, a sprocket wheel carrying member secured to the input shaft and extending generally radially therefrom, a first sprocket wheel co-axiallyy mounted on the output shaft, at lest one drive sprocket wheel assembly mounted on the sprocket wheel carrying member, each drive sprocket wheel assembly at least including a primary and a secondary sprocket wheel, at least one drive sprocket assembly in which the primary and secondary sprocket wheels are adapted to be releasably locked in a desired rotational position relative to one another, a chain extending about the first sprocket wheel and the primary sprocket wheel of the or each individual drive sprocket wheel assembly, a second sprocket wheel rotatably received on the output shaft, a further chain extending about the second sprocket wheel and the secondary sprocket wheel of the or each individual drive sprocket wheel assembly, and means for controlling the speed of rotation of said second sprocket wheel to control the speed of rotation of said output shaft.

Claim 3

A transmission unit in accordance with claim 1 wherein the second sprocket wheel is secured to a sleeve rotatably received on the output shaft and means are provided for controlling the speed of rotation of the sleeve to control the speed of rotation of the output shaft.

Claim 4

A transmission unit in accordance with claim 2 wherein the sleeve is adapted to drive a hydraulic pump having a fluid inlet and outlet, the fluid outlet having valve means for controlling the fluid output of the pump to control the speed of rotation of the pump.

Claim 5

A transmission unit in accordance with claim 3 wherEin the valve means includes a ''''on/off'''' valve, a bleed valve and a pressure sensitive valve.

Claim 6

A transmission unit in accordance with claim 1 in which there are two drive sprocket wheel assemblies provided in a diametrically opposed relationship about the axis of rotation of the output shaft, and one of the two drive sprocket wheel assemblies is adapted so that the primary and the secondary wheels may be releasably locked in a desired rotational position relative to one another.

Claim 7

A transmission unit in accordance with claim 5 in which the second sprocket wheel is secured to a sleeve rotatably received on the output shaft and means are provided for controlling the speed of rotation of the sleeve to control the speed of rotation of the output shaft.

Claim 8

A transmission unit in accordance with claim 6 in which the sleeve is adapted to drive a hydraulic pump having a fluit inlet and outlet, the fluid outlet having valve means for controlling the fluid output of the pump to control the speed of rotation of the pump.

Claim 9

A transmission unit in accordince with claim 7 in which the valve means includes an ''''on/off'''' valve, a bleed valve and a pressure sensitive valve.

Claim 10

A transmission unit in accordance with claim 5 in which the claim extending about the second sprocket wheel assembly and the secondary sprocket wheel assembly of a first of said two drive sprocket wheel assemblies also extends about at least a further two separate sprocket wheels each of which is rotatably mounted on said carrying member and the chain extending about the second sprocket wheel and the secondary sprocket wheel of the second of said two drive sprocket wheel assemblies also extends about at least a further two separate sprocket wheels each of which is rotatably mounted on said carrying member.

Claim 11

A transmission unit in accordance with claim 5 in which the two drive sprocket wheel assemblies are each provided with primary, secondary and tertiary sprocket wheels and in which a separate chain extends about each primary sprocket wheel and said first sprocket wheel, a first chain extending about the secondary wheel of each drive assembly and about one side of the second sprocket wheel and a second chain extending about the teritary wheel of each drive assembly and about the side of the second sprocket wheel opposite to said one side.

Claim 12

A transmission unit in accordance with claim 9 in which the second sprocket wheel is secured to a sleeve rotatably received on the output shaft and means are provided for controlling the speed of rotation of the sleeve to control the speed of rotation of the output shaft.

Claim 13

A transmission unit in accordance with claim 11 in which the sleeve is adapted to drive a hydraulic pump having a fluid inlet and outlet, the fluid outlet having valve means for controlling the fluid output of the pump to control the speed of rotation of the pump.

Claim 14

A transmission unit in accordance with claim 12 in which the valve means includes a ''''on/off'''' valve, a bleed valve and a pressure sensitive valve.

Claim 15

A transmission unit in accordance with claim 10 in which the second sprocket wheel is secured to a sleeve rotatably received on the output shaft and means are provided for controlling the speed of rotation of the sleeve to control the speed of rotation of the output shaft.

Claim 16

A transmission unit in accordance with claim 14 in which the sleeve is adapted to drive a hydraulic pump having a fluid inlet and outlet, the fluid outlet having valve means for controlling the fluid output of the pump to control the speed of rotation of the pump.

Claim 17

A transmission unit in accordance with claim 15 in which the valve means includes a ''''on/off'''' valve, a bleed valve and a pressure sensitive valve.

Claim 18

A transmission assembly including a casing in which is housed a transmission unit having an input shaft, an output shaft in co-axial alignment with the input shaft, a sprocket wheel carrying member secured to the input shaft and extending generallY radially therefrom, a first sprocket wheel co-axially mounted on the output shaft, at least one drive sprocket wheel assembly mounted on the sprocket wheel carrying member, each drive sprocket wheel assembly at least including a primary and a secondary sprocket wheel, at least one drive sprocket assembly in which the primary and secondary sprocket wheels are adapted to be releasably locked in a desired rotational position relative to one another, a chain extending about the first sprocket wheel and the primary sprocket wheel of the or each individual drive sprocket wheel assembly, a second sprocket wheel rotatably received on the output shaft, a further chain extending about the second sprocket wheel and the secondary sprocket wheel of the or each individual drive sprocket wheel assembly, a hydraulic pump also housed in the casing, said second sprocket wheel being in driving connection with said hydraulic pump and valve means for controlling the fluid output of the pump.

Claim 19

A transmission assembly including a casing in which is housed a transmission unit having an input shaft, an output shaft in co-axial alignment with the input shaft, a sprocket wheel carrying member secured to the input shaft and extending generallY radially therefrom, a first sprocket wheel co-axially mounted on the output shaft, at least one drive sprocket wheel assembly mounted on the sprocket wheel carrying member, each drive sprocket wheel assembly at least including a primary and a secondary sprocket wheel, at least one drive sprocket assembly in which the primary and secondary sprocket wheels are adapted to be releasably locked in a desired rotational position relative to one another, a chain extending about the first sprocket wheel and the primary sprocket wheel of the or each individual drive sprocket wheel assembly, a second sprocket wheel rotatably received on the output shaft, a further chain extending about the second sprocket wheel and the secondary sprocket wheel of the or each individual drive sprocket wheel assembly, a hydraulic pump also housed in the casing, said second sprocket wheel being in driving connection with said hydraulic pump and valve means for controlling the fluid output of the pump.

Claim 20

A transmission assembly in accordance with claim 17 in which the second sprocket wheel is secured to a sleeve rotatably received on the output shaft, the sleeve being in driving connection with the pump.

Claim 21

A transmission assembly in accordance with claim 18 in which said sleeve and the input shaft to the pump each carry a sprocket wheel around which extend a chain to provide said driving connection.