Speed forward, 12 speed reverse powershift transmission

The present invention provides a 24 forward speed, 12 reverse speed transmission for use in a work vehicle, e.g., an agricultural or industrial tractor. The transmission uses 10 clutches, with six arranged in a speed section and four in a range section. The speed section arrangement can provide six forward and three reverse speeds, while the range section can provide four ranges. Optionally, the transmission may be provided with a selectively engageable power take-off shaft and a selectively engageable front wheel drive take-off. The entire structure provides a very small speed change requirement between the diffrent gear ratios.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to gearset transmissions, and particularly 
large gearset transmissions with a wide variety of speeds suitable for use 
in work vehicles such as agricultural and industrial equipment. 
2. Description of the Related Art 
There are a great many powershift transmissions known having a large 
variety of speeds. Such variety of speeds is particularly useful for large 
vehicles, and especially work vehicles such as agricultural and industrial 
tractors. Such vehicles may need a dozen or more speeds in a very small 
range, e.g., 0.5 to 5 kilometers per hour, and just a few at higher 
speeds, e.g., up to 40 kilometers per hour. 
Such vehicles typically have a large mass, or are under a significant load 
(for example, plowing), so that the change in energy levels between the 
rotating components of the transmission should be held to a minimum 
between any two successive speeds. This is necessary to minimize the time 
required for a shift, thereby allowing a smoother shift and preventing the 
vehicle from coming to a lurching halt. At the same time, the transmission 
size must also be held to a minimum in order to fit into an existing 
vehicle. 
Funk Manufacturing currently produces a powershift transmission for 
Ford/New Holland row crop tractors which provides 18 forward speeds and 9 
reverse speeds. To do this, nine clutches and attendant gears are arranged 
with six clutches in a speed section and three clutches in a range 
section. The six clutches in the speed section can provide nine useable 
gear ratios, while the three clutches in the range section provide two 
forward ranges and one reverse range. 
While at first it might appear that nine additional speeds could be 
provided simply by adding another forward range, this is not practical in 
reality. First, there is the simple limitation of space. Second, and more 
important, the necessary readjustments to the gear ratios of the speed 
gears required so that the bulk of these ranges will still be in the 
desired, limited range of, e.g., 0.5 to 5 kilometers per hour, would 
produce a very undesirable range of reverse speeds. In addition, the 
momentum which must be changed upon shifting from one of these ranges to 
another would be undesirably high. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide a full 
powershift transmission for a work vehicle capable of providing 24 forward 
speeds and 12 reverse speeds. 
This object of the invention is accomplished by providing a design using 10 
clutches, with six clutches in a speed section and four clutches in a 
range section. The clutches and gears in the speed section are arranged to 
produce six forward speeds and three reverse speeds, so that reverse 
becomes a speed rather than a range. The four clutches in the range 
section provide four ranges, resulting in 24 forward speeds and 12 reverse 
speeds. 
With the new design, a range shift is made every six shifts instead of 
every nine shifts, as would be provided in a modified version of the prior 
transmission. The six additional speeds then are useable to reduce the 
speed change between gear steps, reducing the required changes in the 
speeds of the rotating components during shifts. This decreases the time 
required for shift and allows smoother shifting. 
Preferably, the transmission also provides direct engine power to an 
optionally engageable power take-off shaft, and modified power to a second 
output shaft, e.g., to drive the forward wheels of a four-wheel drive 
vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
For clarity in the following description, reference numerals for shafts all 
begin with S, reference numerals for gears all begin with G and reference 
numerals for clutches all begin with C. For further clarity, the remainder 
of the reference numerals for a clutch and the corresponding gear are the 
same, e.g., clutch CR engages gear GR. Finally, remaining gears use 
nomenclature indicating upon which shaft they are mounted, e.g., gear G2 
is mounted on shaft S2, and multiple gears mounted to a given shaft are 
indicated by alphabetic letters, e.g., gears G5A and G5B are both mounted 
to shaft S5. 
Turning to FIG. 1, a housing 10 has a plurality of shafts, clutches, and 
gears rotatably mounted therein. Input shaft S1 is shown as having been 
made (for manufacturing convenience) in three parts S1A, S1B, S1C. These 
three parts are rotatably mounted in the housing 10 coaxially, and are 
fixed for rotation together by sleeves 12, 14. They will collectively be 
referred to hereinafter as shaft S1. 
Shaft S1 has an input coupler 16 at one end thereof for receiving input 
motive power from a prime mover (not shown), e.g., a vehicle engine. Gear 
G1A is fixed for rotation with shaft S1. 
Shaft S2 is rotatably mounted in the housing laterally adjacent to shaft 
S1, and has gear G2 fixed for rotation therewith. Shaft S2 also carries 
gears GL, GF2, which are rotatably mounted about shaft S2. Clutches CL, 
CF2 also are mounted around shaft S2 and can engage gears GL, GF2, 
respectively, to fix the gears for rotation with shaft S2. Gear GF2 
continuously meshes with gear G1A. 
Shaft S3 is rotatably mounted in housing 10 laterally adjacent to shafts 
S1, S2, and carries gear G3 fixed for rotation with shaft S3. Shaft S3 
also carries gears GMA, GMB, GR which are rotatably mounted about the 
shaft S3. Gears GMA, GMB preferably are formed as a double gear, as shown. 
Shaft S3 further carries clutch CM, which can engage gears GMA, GMB, and 
clutch CR, which can engage gear GR, to fix them for rotation with shaft 
S3. Gears GR G3 GMA mesh continuously with gears G1A, G2, GL, 
respectively. 
Shaft S4 is rotatably mounted in the housing 10 laterally adjacent to 
shafts S1, S3, and carries gear G4 fixed for rotation with the shaft S4. 
Shaft S4 also carries gears GH, GF1, which are rotatably mounted about 
shaft S4. Shaft S4 further carries clutches CH, CF1 which are engageable 
with gears GH, GF1, respectively, to fix the gears for rotation with the 
shaft S4. Gears GH, G4, GF1 mesh continuously with gears GMB, G3, G1A, 
respectively. 
Shaft S5 is rotatably mounted in the housing 10 laterally adjacent to shaft 
S3, and carries gears G5A, G5B fixed for rotation therewith. Gear G5A 
meshes continuously with gear GMB. 
Shaft S6 is rotatably mounted in the housing 10 laterally adjacent to shaft 
S5, and carries gear G6 fixed for rotation therewith. Shaft S6 also 
carries gear GD, which is rotatable about shaft S6. Clutch CD is mounted 
about shaft S6, and is engageable with gear GD to fix the gear for 
rotation with shaft S6. Gear GD meshes continuously with gear G5B. 
Shaft S7 is rotatably mounted in the housing 10 laterally adjacent to shaft 
S6, and carries gear G7 fixed for rotation therewith. Gear GB is rotatably 
mounted about shaft S7. Clutch CB is carried by shaft S7 and is engageable 
with gear GB to fix the gear for rotation with the shaft S7. Gears GB, G7 
mesh continuously with gears G6, GD, respectively. 
Output shaft S8 is rotatably mounted in the housing 10 laterally adjacent 
to shaft S7, and carries gears G8B, G8C fixed for rotation therewith. Gear 
G8C preferably is a conical gear, and provides output motive power, e.g., 
by engaging the ring gear 18 of a differential for driving the wheels of 
the vehicle in which the transmission is used. Gear with GB. 
Shaft S9 is rotatably mounted in the housing 10 laterally adjacent to shaft 
S8 and carries gear G9 fixed for rotation therewith. Gear GA is rotatably 
mounted about shaft S9. Clutch CA also is carried by shaft S9 and can 
engage gear GA to fix the gear for rotation with the shaft S9. Gear GA 
meshes continuously with gear G8B. 
Shaft S10 is rotatably mounted in the housing 10 laterally adjacent to 
shafts S5, S9, and carries gears G10A, G10B fixed for rotation therewith. 
Gear GC also is rotatably mounted about shaft S10. Clutch CC is engageable 
with gear GC to fix the gear for rotation with shaft S10. Gears GC, G10B, 
G10A mesh continuously with gears GA, G9, G5B, respectively. 
As will be apparent from the drawing, shafts S2, S3, S4 are of 
substantially the same size and configuration, and are positioned in a 
first group with their ends largely in common planes. Similarly, shafts 
S6, S7, S9, S10 are very similar in structure and are positioned in a 
second group largely with their ends in common planes. These groups of 
shafts then are positioned in longitudinally adjacent to each other, with 
the gears on shaft S5 serving to transmit power from one the gears in one 
group of shafts to the other. 
A selectively engageable power take off (PTO) shaft may be provided, if 
desired. To do this, an additional gear G1B is fixed for rotation with the 
shaft S1. Shaft S11 is rotatably mounted in the housing 10 adjacent to the 
end of shaft S1 opposite from the input coupler 16. Gear GP is rotatably 
mounted about shaft S11. Shaft S11 also carries clutch CP, which is 
engageable with gear GP to fix the gear for rotation with shaft S11. Gear 
GP continuously meshes with gear G1B. Finally, the shaft S11 carries a PTO 
coupler 28 at one end thereof. 
Similarly, an additional output shaft may be provided, e.g., for front 
wheel drive on a four-wheel drive vehicle. An additional gear G8A is fixed 
for rotation with shaft S8. Shaft S12 is positioned laterally adjacent to 
shaft S8. Gear G12 is mounted to shaft S12 by splines 20, which allow the 
gear to slide along shaft S12, but fix it for rotation with the shaft. 
Gear G12 is movable between a first position meshing with gear G8A and a 
second position disengaged from gear G8A. A shift mechanism 22, including 
the usual shift fork, cam rods, etc., is provided to move the gear G12 
along the shaft S12, into and out of engagement with the gear G8C. Such 
shift mechanisms are well known to one of ordinary skill e.g., for 
providing power to the front wheels of a 4-wheel drive tractor. 
Numerous bearings and oil passages for operating the various clutches are 
illustrated in the drawings. Such bearings and control mechanisms are well 
known to one of ordinary skill in the art, and have been omitted for 
clarity in many of the shafts. It is to be understood that they would be 
provided in the usual fashion. 
FIG. 2 is a schematic representation of a transmission shown in FIG. 1. Due 
to the "unwrapping" all of the transmission in the cross-section taken in 
FIG. 1, not all of the gears are shown meshing with the gears with which 
they actually mesh. Any such situation is shown in the schematic by the 
use of dashed lines. 
In a preferred embodiment, the gears shown in the drawing have the number 
of teeth on each gear shown in Table 1: 
TABLE 1 
______________________________________ 
Tooth 
Gear Count 
______________________________________ 
GA 40 
GB 40 
GC 81 
GD 40 
GH 67 
GMA 67 
GMB 53 
GL 53 
GF1 54 
GF2 48 
GR 54 
GP 71 
G1A 39 
G1B 22 
G2 60 
G3 60 
G4 60 
G5A 41 
G5B 35 
G6 81 
G7 81 
G8A 32 
G8B 80 
G9 81 
G10A 81 
G10B 40 
G12 38 
______________________________________ 
OPERATION 
It is believed that the method of operation of the present invention will 
be readily apparent to one of ordinary skill in the art from the foregoing 
description. 
Generally, a range A, B, C, D is chosen by activation of one of clutches 
CA, CB, CC, CD. A direction and speed then is chosen by activating one of 
clutches CF1, CF2, CR and one of clutches CL, CM, CH. Various combinations 
of these activations can provide 24 forward speeds and 12 reverse speeds. 
In particular, the clutches can be engaged as shown in Tables 2A and 2B. If 
gears having the teeth counts shown in Table 1 are used, the resulting 
gear ratios will be those shown in Tables 2A and 2B. 
TABLE 2A 
__________________________________________________________________________ 
Clutch activated 
Gear 
CA CB CC CD CH CM CL CF1 
CF2 
CR Ratio 
__________________________________________________________________________ 
F1 X X X 12.691 
F2 X X X 11.281 
F3 X X X 10.039 
F4 X X X 8.924 
F5 X X X 7.942 
F6 X X X 7.059 
F7 X X X 6.267 
F8 X X X 5.571 
F9 X X X 4.958 
F10 X X X 4.407 
F11 X X X 3.922 
F12 X X X 3.486 
F13 X X X 3.095 
F14 X X X 2.751 
F15 X X X 2.448 
F16 X X X 2.176 
F17 X X X 1.937 
F18 X X X 1.722 
F19 X X X 1.528 
F20 X X X 1.359 
F21 X X X 1.209 
F22 X X X 1.075 
F23 X X X 0.956 
F24 X X X 0.850 
__________________________________________________________________________ 
TABLE 2B 
__________________________________________________________________________ 
Clutch activated 
Gear 
CA CB CC CD CH CM CL CF1 
CF2 
CR Ratio 
__________________________________________________________________________ 
R1 X X X -12.691 
R2 X X X -10.039 
R3 X X X -7.942 
R4 X X X -6.267 
R5 X X X -4.958 
R6 X X X -3.922 
R7 X X X -3.095 
R8 X X X -2.448 
R9 X X X -1.937 
R10 X X X -1.528 
R11 X X X -1.209 
R12 X X X -0.956 
__________________________________________________________________________ 
Various modifications may easily be made to the present invention by one of 
ordinary skill in the art. For example, if a PTO output is not desired, 
the entire portion 26 of the housing 10 containing shafts S1C, S11, clutch 
CP and gears G1B, GP may be omitted. Similarly, if front wheel drive is 
not desired, shaft S12 and its attendant components may be omitted. 
Alternatively, if permanent front wheel drive is desired, G12 can be fixed 
in a position engaging meshing continuously with gear G8A, and the shift 
mechanism 22 can be omitted. 
While the invention has been described in conjunction with a specific 
embodiment, it is to be understood that many alternatives, modifications 
and variations will be apparent to those skilled in the art in light of 
the foregoing description. Accordingly, this invention is intended to 
embrace all such alternatives, modifications and variations which fall 
within the spirit and scope of the appended claims.