Multiple speed transmission with auxiliary transfer drive

A multiple speed countershaft transmission with a transfer gear drive driven by one of the countershaft gearsets having a gear on the output shaft driving at the output shaft speed to provide an auxiliary power takeoff from the transmission.

This invention relates to a multiple speed countershaft transmission for a 
vehicle and more particularly to a power takeoff from the transmission 
through a transfer gearbox driven by a gear fastened to and rotating at 
the same speed as the output shaft. The gear on the output shaft forms a 
gearset with a gear on the countershaft with selective clutching on the 
countershaft. 
The conventional tractor has an engine which drives through a transmission 
and a differential to drive the rear wheels on the tractor. Under most 
conditions the rear-wheel drive is satisfactory for providing the traction 
needed on the tractor. Under adverse conditions, however, it may be 
advantageous to provide a front-wheel assist on the tractor. The 
front-wheel assist can be operated through hydraulic means or mechanical 
means. A mechanical drive obviates the need for hydraulic conduits, 
couplings, motors and a large pump to provide the power transmission to 
the front wheels. Accordingly a mechanical drive of the front wheels can 
be provided through a power takeoff from the tractor transmission. This is 
normally done with the transfer gearbox on the transmission which receives 
the power from the transmission which is driving the rear wheels. 
Accordingly this invention provides a cnvenient means through a transfer 
gearbox on the transmission of driving the front wheels. Since the 
transmission is a countershaft transmission, one of the gearsets between 
the countershaft and the output shaft can be used to provide the drive. 
The countershaft gearsets are normally clutched on the output shaft to 
provide the selected gear ratio and the power output to the output shaft 
which drives the differential. By providing a clutch on the countershaft 
instead of the output shaft and fixing a gear of one of the gearsets on 
the output shaft to run synchronously with the output shaft, this gear of 
the gearset provides a drive for the transfer gearbox. Selective clutching 
of this countershaft gearset is provided by a clutch on the countershaft 
which selectively engages and disengages the clutch for this gear ratio. 
The transfer gearbox is always in engagement. The transfer gearbox also 
includes a clutch for selectively engaging and disengaging the front wheel 
drive of the tractor through a separate clutching means. The gear fixed to 
the output shaft provides a dual function, one of a speed ratio in a 
countershaft general as well as an output drive for the front wheel drive 
of the tractor. 
Accordingly, it is an object of this invention to provide selectively 
two-wheel drive and four-wheel drive on a vehicle. 
It is another object of this invention to provide a multiple speed 
countershaft transmission with a shifter fork for selectively shifting a 
gear on the countershaft and a gear on the output shaft to selectively 
provide the desired gear ratio. 
It is a further object of this invention to provide a countershaft 
transmission with a shifter fork operating two clutch collars with one of 
the clutches on the output shaft and the other clutch on the countershaft. 
It is a further object of this invention to provide a vehicle countershaft 
transmission with a gear fixed to the output shaft for rotation at the 
same speed as the output shaft and a clutch on the countershaft of a 
countershaft gearset driving into the output shaft and power takeoff from 
the gear fixed to the output shaft driving into a transfer gearbox for 
selective driving of the front wheels of the vehicle. 
The objects of this invention are accomplished through the use of a vehicle 
countershaft transmission with an input shaft and an output shaft rotating 
on a common axis. A countershaft is rotating on a axis parallel with the 
common axis and a countershaft gearset drives from the input shaft to the 
countershaft with return drive from the countershaft to the output shaft 
through a plurality of countershaft gearsets. Clutching is provided on the 
output shaft to selectively clutch the input shaft to output shaft for 
direct drive or clutches mounted on the output shaft for output through 
the countershaft for selected gear ratios. A gear of one of the gearsets 
between the countershaft and the output shaft is fixed to the output shaft 
with clutching means provided on the countershaft to selectively clutch on 
the countershaft. The gear fixed to the output shaft engages an auxiliary 
drive gear for providing front-wheel drive of the vehicle. A selective 
clutch is also provided for engaging and disengaging the drive for the 
front wheels. Accordingly, the gear fixed to the output shaft provides the 
dual function of a drive gear ratio for the main transmission and a power 
takeoff for auxiliary drive of the front wheels of the vehicle.

FIG. 1 illustrates a side-elevation view of a tractor 1 mounted on the rear 
wheels 2 and front wheels 3. The tractor 1 defines an operator station 4. 
The engine 5 drives through the transmission 6, a differential, and a 
final drive assembly 7 drive the rear axles, of which rear axle 8 is 
shown. The transmission 6 is shifted by the shift lever 9 through 
selective gear ratios for driving the tractor. The front-wheel drive for 
the tractor is selectively engaged through the lever 10 which operates 
through the transfer geardrive 11 to drive through the propeller shaft 12 
to drive the front wheels. 
Referring to FIG. 2 the transmission housing 13 encloses the main 
transmission while the transfer gearcase 14 encloses the transfer 
geardrive for driving the front wheels of the tractor. The shift lever 9 
selectively shifts one of the two shift rails 15 and 16 for shifting the 
vehicle transmission. The shift fork 17 with shoulders 18 and 19 is shown 
operating a clutch collar 24 on the output shaft 20 and clutch engaging 
shoulders 21 and 22 for shifting a clutch collar on the countershaft 39. 
Referring to FIG. 3, the clutch collar 24 reciprocally slides on the clutch 
sleeve 25 carried on spline 30. Similarly the clutch collar 27 slides 
reciprocally of the clutch sleeve 28. The gear 26 is fixed to the output 
shaft by the spline 30. Accordingly, the gear 26 rotates at the same speed 
as the output shaft 20. 
The transmission housing 13 is shown supporting the input shaft 31 and the 
output shaft 20. The bearing assembly 32 mounted in the housing 13 
rotatably supports the input shaft 31 which is mounted for rotation about 
the common axis 33. The rear end of output shaft 20 and pinion 86 are 
rotatably mounted in bearings 82 and 83. The output shaft 20 is rotatably 
mounted in the needle bearing assembly 34 embraced within the central 
opening 35 of the input shaft 31. The input shaft 31 also forms clutch 
teeth 36 for clutching the input and output shafts for direct drive of the 
transmission. Input shaft 31 also forms a drive gear 37 which drives the 
driven gear 38 connected to the countershaft 39 by the spline 40. The 
countershaft 39 is rotatably mounted within the bearing assembly 41 of the 
side wall 92 and bearing 84 of side wall 85 of the transmission housing 
13. The countershaft carries the gears 42, 43 and 44. The spline 40 of the 
countershaft 39 is received within mating splines of the gears 38, 43 and 
44. Gears 43 and 44 provide return drive for the gearsets on the 
countershaft transmission. The sleeve 45 forms a bushing for the gear 42 
which meshes with the gear 26. The gear 42 is permitted to rotate freely 
on the sleeve 45 normally unless the clutch sleeve 27 is engaged and then 
the gear 38 rotates with the gear 42. 
The output shaft 20 carries bushings 48 and 49 for rotatably supporting the 
gears 50 and 51. The gear 50 is provided with clutch teeth 52 while gear 
51 is provided with clutch teeth 53. The clutch sleeve 54 is splined to 
the output shaft 20. Similarly a splined external periphery 55 of sleeve 
54 engages the internal spline of the clutch collar 56. The clutch collar 
56 is selectively engaged by the shift fork 57 mounted on the shift rail 
16. The clutch collar 56 is reciprocated on the clutch sleeve 54 by the 
shift fork 57 to selectively engage the gears 50 or 51 for drive through 
the output shaft 20. The shift fork 17 is mounted on the shift rail 15. 
Accordingly, gears 50, 51 which are rotatably mounted on the output shaft 
20 can be selectively clutched to the output shaft by the clutch collar 
56. The gear 26, however, is connected through the spline 30 to the output 
shaft 20. The shift lever 9 is suitably mounted in the transmission cover 
61 for shifting of the shift rails 15 and 16. The output shaft 20 drives 
through the differential 62 to drive the rear wheels. 
The gear 26, however, being fixed to the output shaft 20 also drives gear 
63 in the transfer gear case 14. Gear 63 drives gear 64 which is freely 
rotatable on shaft 65. Gear 64 drives the shaft 65 and the yoke 66 of the 
universal joint 67 when clutch collar 79 is engaged with gear 64. The 
universal joint 67 drives the propeller shaft 12 to drive the front wheels 
through a suitable differential 68 in the front axle 69 of the tractor. 
The lever 10 selectively operates the clutch collar 79 for engagement of 
the clutch teeth 70 on the gear 64. The clutch collar 79 is carried on the 
shaft 65 for selective engagement for front wheel drive from the 
transmission. The gear 63 is mounted on the shaft 71 of the transmission 
housing and is continually in engagement with the gear 26 to provide power 
takeoff for the front-wheel drive. The shaft 65 is rotatably mounted in 
the bearing assemblies 72 and 73 in the gear case 14. 
The operation of the front wheel drive from the vehicle transmission 6 
operates in the following manner. The input shaft 31 is driven by a 
suitable clutch from the engine 5. The clutch collar 24 selectively 
engages the clutch teeth 36 to provide direct drive to the output shaft 
20. The clutch collar 24 can be reciprocally moved rearwardly on the 
spline 47 to the neutral position. Further rearward movement of shift fork 
17 will engage gear 38 with gear 42 for drive through the countershaft 
gearset 75. The gearset 76 is engaged by the shift fork 57 as it is moved 
forwardly for the clutch collar 56 to engage the clutch teeth 52 of the 
gear 50. Similarly the low speed ratio is engaged by engaging the clutch 
collar 56 with the clutch teeth 53 of gear 51 in which gearset 78 is 
engaged to drive from the countershaft 39 to the output shaft 20. 
Drive from the input shaft 31 to the countershaft 39 is provided through 
the countershaft gearset 89 since the gear 38 is splined to the 
countershaft 39 and the gear 37 is integral with the input shaft 31. 
Selective clutching of the transmission is provided on the output shaft 20 
through the clutch collars 24 and 56. The third speed ratio, however, is 
provided by the shift fork 17 through clutching of the clutch collar 27 to 
engage teeth 81 of the gear 42. This completes the drive from the 
countershaft 39 to the output shaft 20 since the gear 26 is splined to the 
output shaft 20. 
The gear 26 is splined to the output shaft 20 and rotates at the same speed 
as the output shaft 20. The gear 26 is also constantly meshing with the 
idler gear 63 which in turn drives the front-wheel drive gear 64. The 
front-wheel drive gear 64 is clutched to the shaft 65 by the clutch collar 
79 which selectively engages the clutch teeth 70 of the gear 64. This is 
selectively controlled through the manual clutch lever 10. The yoke 66 is 
fixed with shaft 65 for driving the propeller shaft 12 and the front wheel 
drive. 
The gear 26 provides a dual function of a gear in the countershaft gearset 
75 for drive through the transmission in the third speed ratio and also 
continuously driving the transfer gears 63 and 64. This provides a power 
takeoff from the transmission through the transfer gear case 14 for the 
front-wheel drive. The selective engagement of the front wheel drive is at 
the option of the driver by engaging the clutch collar 79 when desired.