Automatic Torque Transmission with Gear Pump Brake

Abstract

An automatic torque transmission with one or more stages, where each stage has a number of available gear ratios. There is a planetary gear train comprising a planet gear on a planet gear carrier, a sun gear, and a ring gear, wherein an input to the planetary gear train is through the planet gear carrier, and wherein the planet gear is configured to drive the sun gear at higher speed and lower torque, and the ring gear at lower speed and higher torque. There is a first differential gear train having a first input side, a second input side, and an output, wherein the sun gear is coupled to the first input side of the first differential gear train and the ring gear is coupled to the second input side of the first differential gear train, thereby combining two inputs into a single output. A brake clutch is configured to be selectively coupled to the ring gear, to provide selective braking of the ring gear so as to selectively transfer drive from the ring gear to the sun gear. A one-way clutch is configured to be selectively engaged or disengaged from the sun gear, to selectively prevent rotation of the sun gear in one direction. The output of the differential gear train is coupled to either another stage of the transmission or to an output differential gear train. The output differential gear train is configured to be locked for forward drive or coupled to a housing for reverse drive. With the one-way clutch disengaged the sun gear will freewheel by rotating in reverse, with no output.

Claims

1. An automatic torque transmission, comprising: at least one stage, each stage defining a plurality of available gear ratios and comprising: a planetary gear train comprising a planet gear mounted on a planet gear carrier, a sun gear, and a ring gear, wherein an input to the planetary gear train is through the planet gear carrier, and wherein the planet gear is configured to drive the sun gear at higher speed and lower torque and the ring gear at lower speed and higher torque; a first differential gear train having a first input side, a second input side, and an output, wherein the sun gear is coupled to the first input side of the first differential gear train and the ring gear is coupled to the second input side of the first differential gear train, thereby combining two inputs into a single output; a brake clutch that is configured to be selectively coupled to the ring gear, to provide selective braking of the ring gear so as to selectively transfer drive from the ring gear to the sun gear; a one-way clutch that is configured to be selectively engaged or disengaged from the sun gear, to selectively prevent rotation of the sun gear in one direction; and a transmission housing; and a gear-pump brake that is configured to slow down and stop a gear; wherein the output of the first differential gear train is coupled to either another stage of the transmission or to an output differential gear train, wherein the output differential gear train is configured to be locked for forward drive or coupled to the housing for reverse drive, and wherein with the one-way clutch disengaged the sun gear will freewheel by rotating in reverse, with no output.

2. The automatic torque transmission of claim 1, comprising a plurality of sequentially connected stages, each stage defining a plurality of available gear ratios.

3. The automatic torque transmission of claim 2, wherein each sequentially connected stage doubles the number of available gear ratios of a previous stage.

4. The automatic torque transmission of claim 1, wherein an output from the transmission comprises at least one of: a gear pump that is configured to provide a variable pressure output; and a sensor that is configured to provide a signal that can be used for automatic control of gear changes.

5. The automatic torque transmission of claim 1, wherein the brake clutch and the one-way clutch are both configured to be set to neutral, and wherein when the brake clutch and one-way clutches are both set to neutral the ring gear and the sun gear will both freewheel and cause the transmission to provide no output drive.

6. The automatic torque transmission of claim 1, wherein with the one-way clutch engaged to the sun gear and the brake not applied to the ring gear, the ring gear will dominate the drive at higher torque and low speed.

7. The automatic torque transmission of claim 1, wherein with the one-way clutch engaged to the sun gear and the and the brake applied to the ring gear, the ring gear will slow down and allow the sun gear to dominate the drive, to accomplish a stepless gear change.

8. The automatic torque transmission of claim 1, wherein an output from the transmission operates at different speeds, and wherein an equal number of forward and reverse speeds are produced by the transmission.

9. The automatic torque transmission of claim 1, further comprising a speed sensor coupled to a transmission output.

10. The automatic torque transmission of claim 9, wherein the speed sensor is configured to provide an output pressure that is proportional to a transmission output speed.

11. The automatic torque transmission of claim 10, wherein the speed sensor output pressure is used for control of the brake clutch on the ring gear, to accomplish automatic gear changes.

12. The automatic torque transmission of claim 9, wherein the speed sensor is configured to generate control pressure.

13. The automatic torque transmission of claim 9, wherein the speed sensor comprises a gear pump.

14. The automatic torque transmission of claim 1, wherein the brake clutch comprises a gear pump.

15. The automatic torque transmission of claim 1, wherein the gear-pump brake is configured to slow down and stop the ring gear.

16. An automatic torque transmission, comprising: at least first, second, and third sequentially connected stages, each stage defining a plurality of available gear ratios and comprising a planetary gear train comprising a planet gear mounted on a planet gear carrier, a sun gear, and a ring gear, wherein an input to the planetary gear train is through the planet gear carrier, and wherein the planet gear is configured to drive the sun gear at higher speed and lower torque and the ring gear at lower speed and higher torque, a first differential gear train having a first input side, a second input side, and an output, wherein the sun gear is coupled to the first input side of the first differential gear train and the ring gear is coupled to the second input side of the first differential gear train, thereby combining two inputs into a single output, a brake clutch that is configured to be selectively coupled to the ring gear, to provide selective braking of the ring gear so as to selectively transfer drive from the ring gear to the sun gear, a one-way clutch that is configured to be selectively engaged or disengaged from the sun gear, to selectively prevent rotation of the sun gear in one direction, and a gear-pump brake that is configured to slow down and stop the ring gear, a transmission housing; and wherein the output of the first stage is coupled to a second stage of the transmission, and the output of the last stage is coupled to an output differential gear train, wherein the output differential gear train is configured to be locked for forward drive or coupled to the housing for reverse drive, and wherein with the one-way clutch disengaged the sun gear will freewheel by rotating in reverse, with no output; wherein the brake clutch and the one-way clutch are both configured to be set to neutral, and wherein when the brake clutch and one-way clutches are both set to neutral the ring gear and the sun gear will both freewheel and cause the transmission to provide no output drive; wherein with the one-way clutch engaged to the sun gear and the brake not applied to the ring gear, the ring gear will dominate the drive at higher torque and low speed and wherein with the one-way clutch engaged to the sun gear and the and the brake applied to the ring gear, the ring gear will slow down and allow the sun gear to dominate the drive, to accomplish a stepless gear change; and wherein an output from the transmission operates at different speeds, and wherein an equal number of forward and reverse speeds are produced by the transmission.

17. The automatic torque transmission of claim 16, wherein the last stage further comprises a differential gear set with manual control, to provide reverse drive.

18. The automatic torque transmission of claim 16, further comprising a control system comprising a fluid pressure pump with a manual override valve, to inhibit unintended starts.

19. A gear pump brake, comprising: two gears that are intermeshed so as to move together; a fluid in a volume where the gears are intermeshed; and a close-fitting shoe that overlaps the volume where the gears are intermeshed, wherein the show is configured to be moved from an open position where the gears move freely to a clamped position where the gears are clamped or difficult to move.

20. The gear pump brake of claim 19, used to change gears in an automatic transmission or used to apply braking to a rotating object.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic cross-sectional illustration of a single stage automatic torque transmission.

[0024] FIGS. 2A-2C illustrate a planetary gear train and two options for use thereof.

[0025] FIG. 3 is a schematic cross-sectional illustration of a differential gear train.

[0026] FIG. 4 is a schematic cross-sectional illustration of a planetary gear train coupled to a differential gear train.

[0027] FIG. 5 is a schematic cross-sectional illustration of a differential gear train that accomplishes forward and reverse drive.

[0028] FIG. 6 is a schematic cross-sectional illustration of a gear pump brake clutch for the transmission.

[0029] FIGS. 7A-7C are three schematic cross-sectional illustrations of different configurations of planetary gear trains.

[0030] FIG. 8 is a schematic cross-sectional illustration of a two stage automatic torque transmission.

[0031] FIG. 9 is a schematic cross-sectional illustration of a three stage automatic torque transmission.

[0032] FIG. 10 illustrates an example transmission with automatic transmission control.

[0033] FIG. 11 illustrates torque in the planetary gear train when the planet gear is driving.

[0034] FIGS. 12A and B illustrates the basic principle of a gear pump brake.

[0035] FIGS. 13A-D illustrate the preferred embodiment of the gear pump brake.

DETAILED DESCRIPTION

[0036] FIG. 1 illustrates a single stage automatic torque transmission 10. Transmission 10 utilizes a planetary gear train 30 at the input side of the single stage. The black dots in the drawings indicate a point of connection of elements of the transmission. Transmission input 11 drives planet gear carrier 15, which drives planet gear 14. Planet gear 14 is engaged with sun gear 13 and ring gear 12 and so distributes the drive to the ring gear and sun gear. Ring gear 12 is coupled to differential bevel gear 16 of the differential gear train. Sun gear 13 is coupled to differential bevel gear 17 of the differential gear train. The ring gear, having higher torque, will drive bevel gear 16. With any resistance from the differential gear train output 18, bevel gear 16 will drive bevel gear 17, which is connected to the sun gear 13, in reverse direction. In this condition the transmission will be free-wheeling in neutral. To engage the transmission, one-way clutch 20 stops the reverse motion of the sun gear 13, and drives output 18 of the differential gear train. This arrangement provides low speed higher torque to the output. To change to the higher speed, brake clutch 21 will slow the ring gear 12 and thus share the drive with the sun gear 13, which is higher speed at lower torque. When ring gear 12 stops, sun gear 13 will take over the drive, at higher speed. As explained in more detail elsewhere herein, speed sensor 22, which is coupled to transmission output 23, can provide a signal that is used to control clutches 20 and 21. Also as further explained below, lock sleeve 19 can be used to switch between forward and reverse.

[0037] The range of input revolutions and output revolutions of the planetary gear train of FIG. 1 is described in more detail in FIGS. 2A-2C. This is only one specific, non-limiting example of the particular gears used in a planetary gear train. Other gears/gear ratios can be used, to accomplish different results as would be apparent to one skilled in the technical field. Planetary gear train 30 comprises planet carrier (input) 15, planet gear 14 (with 12 teeth), sun gear 13 (with 12 teeth), and ring gear 12 (with 36 teeth). FIG. 2B illustrates one situation, where sun gear 13 is locked (as indicated by the dark black coloring), while planet gear 14 and ring gear 12 are free to rotate. For one rotation of planet carrier 15, the ring gear rotates 1.33 times. FIG. 2C illustrates a second situation, where ring gear 12 is locked, while planet gear 14 and sun gear 13 are free to rotate. For one rotation of planet carrier 15, the sun gear rotates 4 times.

[0038] FIG. 3 illustrates differential gear train 40 with input 41 from a sun gear, input 42 from a ring gear, bevel gear 43 that is coupled to input 41, bevel gear 44 that is coupled to input 42, and bevel gear 45 that is coupled to output 46. Gears 43 and 44 are the same size. The following Table 1 describes the ranges of inputs and resulting outputs.

TABLE-US-00001 TABLE 1 Input Resulting Output Input through 41. Output through 42, equal to: input 41 in Output 46 locked. reverse. Input through 42. Output through 41, equal to: input 42 in Output 46 locked. reverse. Input through 41 and 42 Output through 46, equal to: (input 41 + input 42) 2 Input through 41. Output through 46 equal to: input 41 2 Input 42 locked. Input through 42. Output through 46 equal to: input 42 2 Input 41 locked.

[0039] FIG. 4 illustrates a combination of planetary gear train 30 (FIG. 2A) and differential gear train 40 (FIG. 3). Input is via planet gear carrier 15. The following Table 2 describes the types of rotations of the planetary and differential gear trains and the resulting outputs. The formula to calculate the output is: (input 1+input 2)2.

TABLE-US-00002 TABLE 2 Input rotations Output rotation (from output 46) Ring gear 1 + sun gear 1 0 Ring gear 1 + sun gear 0 Ring gear 1 + sun gear 1 1 Ring gear 0 + sun gear 4 2

[0040] FIG. 5 illustrates a manner in which the differential gear train can be used to operate the transmission in forward and reverse drive. Differential gear train with forward and reverse drive 60 includes input 61, output 62, bevel gear ring 63, bevel gear lock sleeve 64, and housing 65. Lock sleeve 64 is coupled to bevel gear ring 63. Lock sleeve 64 is movable to two positions. In one position it locks bevel gear ring 63 to input 61. In the other position it locks bevel gear ring 63 to housing 65. To operate in forward, lock sleeve 64 is operated such that bevel gear ring 63 is locked to input 61. To operate in reverse, lock sleeve 64 is operated such that bevel gear ring 63 is locked to housing 65. Other manners of selectively locking the differential to the housing so as to accomplish reverse drive are contemplated herein. A result is that all of the speeds are available in both forward and reverse.

[0041] FIG. 6 illustrates a non-limiting example of a gear pump 70 that can be used as a brake clutch for the transmission. A pair of gears 71 closely meshing inside a close-fitting housing 72 carry fluid from fluid inlet (input) 73 to close fitting chamber 74 and then fluid outlet 75. Plunger 76, supported by spring 77, controls the orifice size of outlet 75 via motion of conical closure element 81. Pressure applied through pressure inlet 78 to cylinder 79 pushes piston 80 and plunger 76, compresses spring 77, and reduces or closes orifice 75. When orifice 75 is fully open there is no pressure buildup in chamber 74 and gears 71 rotate freely. As the orifice 75 closes, the fluid pressure in chamber 74 builds up and slows down rotation of gears 71 and acts as a brake. When orifice 75 is fully closed pressure in chamber 74 builds up sufficiently to stop gears 71 from rotating and act as a clutch.

[0042] FIGS. 7A-7C illustrate three variations of a planet gear for a planetary gear train. Planetary gear train 90, FIG. 7A, includes single pinion planet gear 91. Planetary gear train 92, FIG. 7B, includes double pinion planet gear 93. Planetary gear train 94, FIG. 7C, includes a different double pinion planet gear 95. Double pinion planet gears can be used to drive the sun and ring gears at different rates, depending on the pitch of the two toothed gear portions that are coupled to the sun and ring gears, as depicted in FIGS. 7B and 7C.

[0043] The transmission 100 shown in FIG. 8 is a two-stage transmission, with four forward ratios, neutral, and reverse drive. Simple gear pumps, configured as clutches, provide for smooth transfer between gear ratios.

[0044] In transmission 100 the drive comes into a first planetary gear train 120 through the planet gear carrier 101. The planet gear 104 distributes drive to ring gear 102 and sun gear 103. Ring gear 102 drives differential bevel gear 105, and sun gear 103 drives opposed differential bevel gear 106 of first differential gear train 121. Ring gear 102 having higher torque will drive bevel gear 105. With any resistance from differential gear train output 110, bevel gear 107 will drive bevel gear 106, which is connected to the sun gear 103, in reverse direction. In this condition the transmission will be free-wheeling in neutral. To engage transmission 100 one-way clutch 108 stops the reverse motion of sun gear 103 and drives output 110 of first differential gear train 121. This arrangement provides low speed higher torque to the output. To change to the higher speed brake clutch 109 will slow ring gear 102 and thus share the drive with sun gear 103, which is higher speed at lower torque. When ring gear 102 stops, sun gear 103 will take over the drive, at higher speed.

[0045] Drive from the first stage is transferred to the second stage with speed reduction gears 111. The second stage works the same way as the first stage, with second planetary gear train 122 and second differential 123, except that it has added another (third) differential gear train 124, to add reverse drive, and a gear pump 114 configured to generate pressure controlled by the speed for automatic control of the gear change. Sleeve 112 locks the center bevel gear to the transmission output drive for forward drive, or locks it to the housing 125 for reverse drive of output 113. Control gear pump 114 is coupled to the output 113.

[0046] To simplify the automatic gear change only two ratios per stage are used. However, there could be more than two gear ratios per stage. On startup, brake clutches 109 are opened and one way clutches 108 are closed, so drive starts at low speed and high torque. The clutch 109 for each stage is set for a different pressure, to match set speeds. As the speed increases, pump 114 increases pressure and sequentially closes brakes 109 at preset speeds. This way the gear change is stepless, automatic, and linked to speed. To use all available ratios a more elaborate gear matching and control system can be used.

[0047] The transmission 130 shown in FIG. 9 is a three-stage transmission being the same as in FIG. 8 except that one more stage 132 is added and in one stage the sun gear does not have a one-way clutch and in the other stages a one-way clutch couples the sun gear to the ring gear. This puts the transmission into a neutral state. To start rolling, brake clutch 109, on the stage without the one-way clutch, is set to reduce torque of the ring gear to equal torque of the sun gear, to prevent the sun gear rotating in reverse. Coupling of the sun gear to the ring gear with a one-way clutch, will prevent the differential gear train from dividing high torque by two. This is compensated by the speed reduction gears 111.

[0048] The transmission 10 shown in FIG. 1 is a single-stage transmission being the same as in FIG. 8, except that it has only one stage, and input is through a reduction gear to extend output range.

[0049] Table 3 includes gear ratios at each stage for an exemplary four-stage transmission, each stage having the same gear set. Table 4 includes gear ratios for a similar four-stage transmission, but with each stage having a different gear ratio as set forth in the table. The different gear ratios can be accomplished with gears having different pitch diameters.

TABLE-US-00003 TABLE 3 stage 1 stage 2 stage 3 stage 4 0.666 0.4435 0.2954 0.1967 1.332 0.879 0.585 2 1.332 0.879 0.585 4 2.664 1.774 0.887 0.585 2.664 1.774 2.664 1.774 8 5.328 0.588 1.758 1.758 5.328 1.774 5.328 5.328 16

TABLE-US-00004 TABLE 4 Low gear ratio 0.60 0.70 0.80 0.33 High gear ratio 2.00 1.70 1.30 1.00 stage 1 stage 2 stage 3 stage 4 0.60 0.42 0.34 0.11 2.00 1.40 1.12 0.37 1.02 0.82 0.27 3.40 2.72 0.90 0.55 0.18 1.82 0.60 1.33 0.44 4.42 1.46 0.34 1.12 0.82 2.72 0.55 1.82 1.33 4.42

[0050] FIG. 10 illustrates a three-stage self-contained modular automatic transmission that does not require a clutch or external control. Stage 1 (200) includes planetary gear train with planet gear carrier (145) with planet gear (146) mounted on it, sun gear (147), shaft (148) that connects sun gear to one side of the differential gear train (150), ring gear (149) with a gear that is the other side of the differential gear train (150), selectively engaging one-way clutch (151) that (when engaged) prevents sun gear (147) going into reverse, gear pump brake (141), illustrated in more detail in FIG. 13, that slows down and stops ring gear (149) to transfer drive to sun gear (147), pump (142) with safety valve (143) to provide pressure to the cylinder (144) that engages one-way clutch (151) and gears (152) that transfer drive to the next stage. Input to stage 1 (200) planetary gear train is through planet gear carrier (145) driving ring gear (149) and sun gear (147) blending into single output with differential gear train (150), ring gear (149), having more torque will drive sun gear (147) through differential gear train (150) in reverse with no output neutral state. As the speed increases the pump (142) will develop enough pressure for cylinder (144) to engage one-way clutch (151) and stop sun gear (147) from going in reverse. So, ring gear (149) drives differential gear set (150) at high torque low speed. Differential gear set (150) transfers drive to stage 2 (250) with gears (152) that further increase torque and reduce speed.

[0051] Stage 2 (250) is functionally the same as stage 1 (200) except that one-way clutch (157) is fixed and sun gear (154) cannot run in reverse, so ring gear (153) drives differential gear train (156) at higher torque. Differential gear train (156) drives input to stage 3 (300).

[0052] Stage 3 (300) is functionally the same as stage 2 (250) except that it has another differential gear set with manual control (160) to provide reverse drive. Ring gear (155) drives differential gear train (159) at higher torque. The differential gear train (159) also drives pump (142) that provides pressure to gear pump brakes (141) to slow down and stop the ring gears and transfer the drive to the sun gears with higher speed. Shaft (158) provides mounting for one-way clutches. Differential gear (161) is the transmission output.

[0053] Gear pump brakes (141) have a different pressure setting for each stage, stage 1 (200) being the highest and stage 3 (300) the lowest. As the pressure builds up from pump (142), driven by output (159), the gear pump brakes (141) will slow down and stop ring gear (155) transferring drive to sun gear (154) at higher speed. The same follows in stages 2 (250) and 1 (200). As the speed slows down the process is reversed all the way to a neutral state.

[0054] FIG. 11 is a schematic of a planetary gear train showing a size/torque relation where planet gear (146) is the same size as the sun gear (147), and ring gear (149) is three times bigger. The relative size of the sun and planet gears determines the ratio between ring gear and sun gear outputs. Making the planet gear larger than the sun gear increases the ratio between outputs, and making the planet gear smaller than the sun gear decreases the ratio between outputs

[0055] FIGS. 12A and B illustrate the basic principle of the gear pump brake. FIG. 12A shows gear (201) in close mesh with gear (202) enclosed in a close-fitting shoe (203) and immersed in a liquid (204). As the gears mesh, they expel fluid carried into mesh by gear teeth, that escapes through the gap between shoe and gears. FIG. 12B shows closing the gap between shoe and gears that generates braking pressure (205) to slow down and stop the gears.

[0056] FIGS. 13A, B, C, and D illustrate the preferred embodiment of the gear pump brake. A gear pump brake, comprising: main gear (230), second gear (231) close fitting shoe (234) pivoting on the center of gear (231), fluid (232), and control (235-237). A main gear (231) and a secondary gear (232) that are meshed together in a meshing region such that the main gear drives the secondary gear; a close-fitting shoe (234) pivoting on the center of gear (231) and partially enclosing the meshing region, wherein in an open position (FIG. 3A) the shoe is spaced from one gear to define a shoe-gear gap (233); wherein at least some of the meshed gears and the shoe are immersed in fluid such that rotation of the gears moves fluid through the shoe-gear gap; and a control mechanism that is configured to vary the width of the shoe-gear gap between gear teeth into meshing gears. The control mechanism is schematically depicted as a hydraulic cylinder (235) with piston (236) that moves spring (235) to pivot shoe (234). Meshing gears expel fluid from between gear teeth and make fluid escape through the shoe-gear gap; and control mechanism that is configured to vary the width of the shoe-gear gap that determines pressure of escaping fluid. The pressure created by meshing gears generates braking torque to resist rotation. FIG. 13B shows the gear pump in the locked state. FIG. 13C shows a cross-section of gear (230) and close-fitting shoe (234) taken along line C-C, FIG. 13A. (233) is a variable gap between gear (230) and a close-fitting shoe (234), that controls pressure, by restricting flow of fluid displaced by meshing gears. (238) are clamping surfaces on gear (230) and shoe (234) that clamp gear (230) to prevent rotation. FIG. 13D shows the gear pump configured as a two-way brake.

Description of Transmission Control System (See FIG. 10).

[0057] With the planetary gear train components relative size shown in FIG. 11, the following refers to FIG. 10. With planet gear carrier (145) driving planet gear (146) 1.0 revolution and sun gear (147) locked, the ring gear (149) will revolve 1.333 turns with a torque of 0.75 units. With ring gear locked, sun gear (147) will revolve 4 turns with a torque of 0.25 units. Outputs from ring gear (149) and sun gear (147) are blended in differential gear train (150) into a single output, with speed divided by 2 and torque multiplied by 2, making output from each stage from 0.666 revolutions (ring gear driving) to 2 (sun gear driving), making speed ring/sun (0.666/2), and torque ring/sun (1.5/0.5) of the input. This input/output relation is the same for stages 2 (250) & 3 (300). Output from stage 1 (200) is transferred to stage 2 (250) through gear set (152), which reduces speed of ring/sun to (0.5/1.5) and increases torque of ring/sun to (2/0.666) of the input.

[0058] The torque output from stages 2 (250) and 3 (300) is input from previous stage times (1.5 with ring gear driving) or (0.5 with sun gear driving), and speed output to from stage 2 (250) and 3 (300) is input from previous stage times (0.666 input units with ring gear driving or 2 input units with ring gear driving).

[0059] The control system is made up of fluid pressure pump (142) with manual override valve, (143), (to prevent unintended start), gear pump brake (141) (to slow down and stop ring gear (149), cylinder (144) (to engage one-way clutch (151) to stop sun gear (147) going into reverse, and three gear pump brakes (141) to slow down and stop ring gears.

[0060] When input (145) starts, there is not enough pressure coming out of pump (142) to engage one-way clutch (151), so ring gear (149) drives, through differential gear train (150), sun gear (147) in reverse and there is no output, (neutral state).

[0061] As the input speed increases, over idling speed, pressure builds up enough to engage one-way clutch (151) and prevent sun gear going into reverse. With sun gear stopped ring gear (149) high torque, low speed, drives differential gear set (150) and transfer drive to stage 2 (250) trough gear set (152). In stages 2 (250) and 3 (300) one-way clutches (157) are permanently engaged, preventing sun gears (154) going into reverse, allowing ring gear (155) to drive. With all ring gears free to rotate, output to differential gear train (159) is high torque at low speed.

[0062] The output (159) drives another pump (142) that provides pressure to the gear pump brakes (141), that slow down and stop ring gear, gradually transferring drive from ring gear to sun gear, high speed, low torque.

[0063] Each gear pump brake (141) has different rating, so as speed and pressure increases, ring gears are sequentially slowed and stopped, with stepless change into higher gear.

[0064] With relative gear sizes of planetary gear train shown in FIG. 11, Table 5 below gives examples of the torque and speed outputs ratios.

TABLE-US-00005 TABLE 5 Stage 1 Stage 2 Stage 3 drive drive drive Torque Speed Ring Ring Ring 2 1.5 1.5 = 0.5 0.666 4.5 0.666 = 0.222 Ring Ring Sun 2 1.5 .666 = 0.5 0.666 1.999 2 = 0.666 Ring Sun Sun 2 .666 .666 = 0.5 2 2 = 2 .88 Sun Sun Sun .5 .666 .666 = 1.5 2 2 = 6 .22

[0065] When the speed decreases the gears will change down all the way to neutral.

[0066] A number of implementations have been described. Nevertheless, it will be understood that additional modifications may be made without departing from the scope of the inventive concepts described herein, and, accordingly, other embodiments are within the scope of the following claims.