US2685210A

US2685210A - Overdrive system

Info

Publication number: US2685210A
Application number: US208175A
Authority: US
Inventors: Harry F Heisler
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-01-27
Filing date: 1951-01-27
Publication date: 1954-08-03
Anticipated expiration: 1971-08-03

Description

Aug. 3, 1954 H. F. HEISLER' v ovERnRIVE SYSTEM 6 Sheets-Sheet 2 Filed Jan. 2v, 1951 I'II' Aug. 3, 1954 H. F. HELSLER 2,685,210 ovERDRIVE SYSTEM I Fil'edJan. 27, 1951 I l v 6 Sheets-Sheet 3 A1193, 1954 I H. F. HElsLER 2,685,210v

OYERDRIVE' SYSTEM Filed Jan. 27,'1951 A ZAw/elnor.' Jarry Fu/ezlsler .B www Aug` 3, 1954 H. F. HE|sLER 2,685,210

i OVERDRIVE SYSTEM Filed Jan. 27, 1951 6 Sheets-Sheet 5 2 il J 12 132\\ 3 Aug-.3, 1954 H. F. HElsLER y2,685,210

ovERnRIvE SYSTEM Filed Jan. 27; 1951 6 Sheets-Sheet 6 l N V EN TOR.

Patented Aug. 3, 1954 UNITED STATE ATENT OFFICE Claims.

This particular application is a continuationin-part application of my pending application, Serial No. 150,852, on an Overdrive System, filed on March 21, 1950.

This invention relates to an overdrive system, and more particularly to an overdrive system which is easily adapted to existing transmissions of tractors and the like. The range of power speeds of farm tractors is very limited and the top speed of the usual power speed range is relatively low. For example, a typical tractor may have four power speeds ranging from 21/2 miles per hour to about 51/2 miles per hour. Tractors are also often equipped with a fth speed of about 18 miles per hour which is attainable only when there is very little or no load on the tractor, and which speed is attained by connecting the drive shaft directly to the supply of power, thereby by-passing the countershaft. The tractors power speeds are designed low because the loads carried or hauled by tractors are usually very large and greater pulling power or torque is developed at lower speeds.

However, there are many occasions when the tractor is moving between jobs when it is unloaded or partially unloaded and higher power speeds are desirable. When those occasions arise, the tractor is unable to meet the demand for higher speeds, because of the low gear ratios which are available in the transmission. The high direct drive speed is often impractical if the tractor is partially loaded or if the terrain over which the tractor is moving is rough. Thus it is desirable to provide intermediate power speeds having values between the highest of the existing power speeds and the high direct drive speed. While it is true that the entire transmission could be changed to give these higher power speeds, the high torque, lower power speeds would be lost in such an arrangement, which would be undesirable.

In adapting an overdrive system to an existing transmission, it is desirable to retain as much as possible of the existing transmission. If possible, it is desirable to integrate the overdrive system with the existing shifting arrangement for the transmission. The adaptation of an overdrive to an existing transmission without losing the original speeds of the transmission requires the use of additional shiftable members l' and means whereby the shiftable members are actuated. The proper use of such additional shiftable members is predicated, in some degree, upon a means for positioning and retaining the shiftable members in predetermined positions.

Thus, one of the objects of this invention is to provide a novel overdrive system for tractors which provides a range of higher speeds without sacricing the existing range of high torque lower speeds.

Another object of this invention is to provide an overdrive system for use within the transmission housing of the vehicle, which may be easily adapted to the existing transmission system.

A further object of this invention is to provide an overdrive system which is designed to be easily tted into the existing transmission housing for a motor vehicle.

A still further object of this invention is to provide a novel overdrive system, which converts an existing four speed transmission into an eight speed transmission, or an existing five speed transmission into a nine speed transmission.

Another object of this invention is toprovide a novel ball poppet means for positioning coaxial members, which are shiftable axially therebetween, with respect to each other in a plurality of predetermined positions.

Still another object of this invention is to provide a novel shifting means which consists of simple and inexpensive linkages for use with the novel overdrive system, which shifting means is easily adapted to the existing transmission structure.

And still a further object of this invention is to provide a novel support means within the transmission housing for performing the dual function of supplying a journal for a rock shaft of the shifting means and for supporting a guide collar for the shifting lingers.

Further objects and advantages of this invention will become apparent as the following description proceeds and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming part of this specication.

A preferred embodiment of the invention is shown in the accompanying drawing, in which- Figure 1 is a cross sectional side View of the drive shaft and the countershaft of a typical transmission for a tractor, which have been modied to include elements of my invention, and shows the shiftable clutch collar, mounted on the countershaft, shifted into the overdrive speed position.

Figure 2 is a top plan view, partly in cross section, of the countershaft and reverse gear shaft of a typical transmission for a tractor, which have been modified to include elements of my 3 invention, which view is taken on line 2 2 of Figure 1.

Figure 3 is an end view, partly in cross section, of the transmission housing and the modified shafts and gears mounted therein, and is taken on line 3-3 of Figure l.

Figure 4 is a cross section View of one of the rock shafts in the overdrive shifting linkage and is taken on line 4-4 of Figure 3.

Figure 5 is an end view, partly in cross section, of the modified drive shaft and countershaft, showing the ball poppet means in more detail, and is taken on line 5 5 of Figure 1.

Figure 6 is another cross sectional end view of the shafts and gears within the transmission housing, and is taken on line E-E of Figure l.

Figure 7 is a top plan View, partly in cross section and partly in elevation, with portions of the transmission housing broken away, of a portion of the overdrive shifting linkage, and is taken on line 1-1 of Figure 3.

Figure 8 is a side view of the part of the overdrive shifting linkage shown in Figure r1, and also shows the actuating rod for the shifting linkage.

Figure 9 is a cross sectional view of the shiftable clutch collar mounted on the countershaft, showing the clutch collar shifted into the regular speed position.

Figure 10 is a cross sectional view of the clutch collar and countershaft, and is taken on line Ill-l 0 of Figure 9.

Figure 11 shows substantially the major parts, other than the shifting linkage, that are supplied for adapting the overdrive system to the existing transmission. The view is similar to that in Figure 2, with the addition of the two gears that are supplied for the drive shaft. These latter two gears are shown in Figure 11, rotated out of vertical position but positioned axially substantially as they would be in the transmission housing. The parts in Figure 11 outlined in dotdash line are parts that are similar to previous existing parts in the transmission but which are, nevertheless, replaced.

Figure 12 is similar to the left-hand half of Figure 1 and shows a modified form of my invention, wherein the relative positions of the power drive gears are reversed, and'wherein a modified arrangement for axially positioning the driven gears is provided.

Figure 13 is similar to the left-hand half of Figure l and shows another modified form of my invention, wherein the second power drive gear is mounted on the extension shaft and the relative positions of the power drive gears are reversed, and wherein a modified arrangement for axially positioning the driven gears is provided.

For the purposes of this description of my invention, I have elected to described the modifications on a typical five speed tractor. The standard arrangement of elements in the tractors transmission housing includes a drive shaft, a countershaft and a reverse gear shaft. The countershaft is journalled in bearings in a pair of opposite walls of the transmission housing. The reverse gear shaft is shorter than the drive shaft or countershaft and is supported at one point in one wall of the transmission housing and supported at another point by a standard located in the transmission shifting chamber, substantially in mid-length thereof.

The drive shaft is journalled at one point in a bearing mounted in a wall of the transmission housing and extends into the transmission shifting chamber. The other support for the drive shaft is a bearing for the extended end of the drive shaft, which bearing is journalled within a concentric recess of the power drive gear. The power drive gear itself has an extension shaft formed integrally therewith and journalled in bea-rings in another wall of the transmission housing. Effectively, the drive shaft is supported by bearings in opposite walls of the transmission housing through the bearing joint in the recess of the power drive gear.

'This power drive gear which is coupled to the source of power is in mesh with a single countergear splined to the countershaft, whereby the countershaft is rotated when the power drive gear rotates. The bearing which is at the end of the drive shaft, and is journalled in the power drive gear recess, permits overriding of the power drive gear on the drive shaft.

Also non-shiftably splined to the countershaft are a pair of spaced double gears, each gear being of a different diameter and adapted to mesh with other gears on the drive shaft, whereby Said drive shaft is rotated at different speeds, One each of the two pairs of double gears correspond to speeds referred to as first, second, third, and fourth. The gear that corresponds to second speed is in mesh with a first gear rotatably mounted on the reverse gear shaft.

The reverse gear shaft is xedly mounted within the transmission housing. The rst gear on the reverse gear shaft is connected by means of a collar, rotatably mounted on the reverse gear shaft, to a second gear. The nrst and second gears and the collar rotate as a unit.

On the drive shaft are two single and one double shiftable gears. These gears are splined to the drive shaft, whereby the rotation of any one of the gears will result in the rotation of the drive shaft. All the gears are adapted to be shifted in opposite directions along the drive shaft. The rst single gear is adapted to engage the gear on the countershaft corresponding to first when shifted in one direction, and to engage the second gear on the reverse gear shaft when shifted in the opposite direction. The engagement with the second gear on the reverse shaft results in rotation of the drive shaft in the reverse direction.

The double gear on the drive shaft is positioned between the spaced pair of double gears on the countershaft. When the double gear is shifted in one direction, one of its gears engages the gear on the countershaft corresponding to second, and when shifted in the opposite direction, the other gear of the double gear meshes with the countershaft gear corresponding to third. Similarly, the second single gear on the drive shaft when shifted in one direction engages the countershaft gear corresponding to fourth.

This second single gear on the drive shaft is also provided with an internally splined recess whereby when it is shifted, in the opposite direction to that wherein the fourth speed gear was engaged, the internal splines engage the teeth of the power drive gear rotatably journalled at the end of the drive shaft, whereby a fifth speed is provided. The internal splines on the second single drive shaft gear engage only a portion of the power drive gear edge. This is provided for by reducing the diameter of the power drive gear over the portion to be engaged. Then the portion of the power drive gear that is not reduced in diameter engages the second single drive shaft gear at a bearing interface and limits the extent of shift of the second single gear. This is desirable to preventI the second single driveshaft gear from being shifted to an interfering position with the single countergear on the countershaft.

As is well known in the art, when any shiftable gear is in mesh, all the other shiftable gears are disengaged.

Referring now to the modified form which incorporates the elements of my invention and, as shown in the figures, there is shown in Figure '1 a transmission housing, generally indicated at I0, enclosing a transmission shifting chamber I I. A power drive gear I2 is part of a double gear I4 integrally formed with extension shaft I6. The extension shaft is journalled by bearing I8 in wall of transmission housing I6. The power drive gear I2 has a recess 22 therein adapted to receive sealed bearing 24.

A drive shaft generally indicated at 26 is journalled at a region intermediate its ends by means of bearing 28 in wall 30 of transmission housing I0. Other support for drive shaft 26 is located at the extended end thereof andcomprises bearing 24 which is secured to drive shaft 26 by means of bolt 32. Thus, the drive shaft 26 is effectively supported by bearings I8 and 28 in

walls

20 and 30 of transmission housing I0 through the bearing joint comprising bearing 24 in recess 22 of power drive gear I2.

The drive shaft 26extends through wall `36 of the transmission housing into chamber 34 within the transmission housing. Mounted on the end of the shaft 26 which extends into chamber 34 is a pinion gear 36 which is the power takeoe for the wheels of the tractor.

A countershaft 38 is shown rotatably mounted in

bearings

40 and 42 which are respectively positioned in

walls

26 and 30 of transmission housing I0. One end of countershaft 38 is provided with an attachment 44 which may be connected to a hydraulic system pump (not shown) so as to actuate the hydraulic system of the tractor. The other end of countershaft 38 is splined as at 46 so as to provide means for driving the auxiliary take-off which powers the attachments to the tractors.

As seen more clearly in Figures 2 and 3, a new reverse gear shaft 48 is xedly mounted in

supports

50 and 52 within the transmission housing. Support 50 is integral with wall 30 of transmission housing and support 52 projects into the transmission housing chamber about midway between

walls

20 and 36 of the transmission housing. A pin 54 extends through support 52 and through reverse gear shaft 48, thereby fixing shaft 48 in position in

supports

50 and 52. The new reverse gear shaft 48 extends beyond support 52 as at 49, to provide a support for a bracket, as will be hereinafter described.

Referring back to the drive shaft and to the power drive gear, as shown in Figure 1, the power drive gear I2 is reduced in diameter over a portion of the gear edge thereof, as indicated at 56. The drive shaft 26 is provided with two single and one double shiftable gears. These gears are splined to the drive shaft 26 and are rotatable therewith and are adapted to be shifted in either direction along the drive shaft 26. The rst shiftable single gear 58 is adapted to engage the gear on the countershaft corresponding to first speed when shifted in one direction and to engage the reverse speed gear when shifted in the opposite direction. The double shiftable gear 60 has two gear faces 62 and 64 thereon. Gear 62 is adapted to engage the second speed gear on the countershaft when the double gear 60 is shifted in one di# rection, and gear 64 is adapted to engage the third speed gear mounted on the countershaft when the double gear 66 is shifted in the opposite direction. Ihe second single shiftable gear 66 is adapted to engage the fourth speed gear when it is shifted in one direction. Each of the shiftable gears 58, 60, and 66 is provided with grooves 59 therein adapted to receive means (not shown) for shifting said gears. The means for shifting these gears, provided in the original transmission, are retained herein and are well known in the art.

The single gear 66 in the original iive speed setup was provided with internal splines to engage the reduced portion 56 of the gear edge of power drive gear I2. In the modified form herein, a portion of the spline length of shaft 26 has been reduced in diameter to eliminate the splines and to provide a bearing surface as at 68. Mounted on the reduced diameter portion 68 of shaft 26 is a ball bearing 10. A second power drive gear 'I2 is mounted on the bearing 'I0 and, therefore, is rotatably mounted on shaft 26. This second power drive gear 'I2 is provided with an internally splined recess 'I4 adapted to engage the reduced diameter portion 56 of the gear edge of power drive gear I2. A snap ring I6 acts to keep the two power drive gears constantly in mesh, so that they rotate as a unit. The shoulder 'I8 in shaft 26 acts to keep the bearing 'I0 axially restrained from movement along the shaft. The greater diameter portion of the gear edge of power drive gear I2 butts against the face of the second power drive gear 'I2 at the interface 80, thereby restraining the gear 'I2 from axial movement in the opposite direction.

The second power drive gear 'I2 has a reduced diameter portion on its gear edge 82, as shown in Figure 1. The shiftable single gear 66 is provided with a splined internal recess 84 which is adapted to engage the second power drive gear 'I2 over the reduced diameter portion 82 of its gear edge, when the shiftable single gear 66 is shifted to the left, as seen in Figure 1. The larger diameter portion of the gear edge of power drive gear I2 provides a bearing interface 86 against which the shiftable single gear 66 butts when it is shifted to the left, as described above. This bearing interface 86 provides a stop for limiting the motion of gear 66 in the direction to the left, as shown in Figure l.

Referring next to the countershaft 38, a first and second driven gear is shown in mesh with the first and second power drive gears. A first driven gear 68 is shown in mesh with power drive gear I2. This first driven gear 88 is rotatably supported on bearings 96 which are mounted on a reduced diameter section 92 of countershaft 38. A second driven gear 94 is rotatably mounted with respect to countershaft 38 and is in mesh with the second power drive gear 12.

Splined to the countershaft 38 is a clutch co1- lar 86 which is rotatable with countershaft 38 and is shiftable in an axial direction thereon. A bearing 98 mounted on the outer periphery of clutch collar 96 is adapted to receive and support the rotatably mounted gear 04. Also splined to countershaft 38 are a pair of double gears |00 and |02. Snap rings |64 are adapted to engage the faces of double gears |06 and |62 to prevent their axial movement along the countershaft 38. Gear |06 of double gear |00 corresponds to a first speed and is adapted to be engaged by rst shiftable single gear 58 mounted on drive shaft 26. Gear |08 of double gear |00 corresponds to the second speed gear and is adapted to receive gear 62 of shiftable double gear 6a mounted on drive shaft 26. Gear of double gear |02 corresponds to thirdspeed and is adapted to receive gear 64 of shiftable double. gear 60 which is mounted on drive shaft 26. Gear ||2 of double gear |02 corresponds to fourth speed and is adapted to receive gear face 61 of the second shiftable single gear 66 mounted on drive shaft 26.

As seen more clearly in Figures 2 and 3, a pair of gears ||4 and ||6 joined together by a collar |8 are rotatably mounted on reverse gear shaft 48. Gear ||4 is in mesh with the second speed `gear on countershaft 38 which is gear |88 of double gear |00. The gear ||6 is adapted to be engaged by the shiftable single gear 58 which is mounted on drive shaft 26.

Thus far the gears and their relationship to each other have been described. The manner of driving the countershaft through the power drive gears will now be disclosed. As set forth above, a clutch collar 85 is splined to shaft 38 and is shiftable in an axial direction thereon. One end of clutch collar 96 has formed thereon a gear |20. The first driven gear 88 has formed therein an internally splined recess |22 which is adapted to receive and engage the teeth of gear |28 when the clutch collar 86 is shifted to the left when viewed as in Figure l, and which position is shown in Figure 9. The second driven gear 94 has an internally splined recess |24 which is adapted to receive and engage the teeth of gear |28 when the clutch collar 96 is shifted to the right, which is the position shown in Figure l. The first driven gear 88 is also provided with an enlarged recess |26 which is of greater diameter than the gear |20 and which is positioned between the splined recesses |22 and |24. When gear |28 is positioned in recess |26, both the irst driven gear 88 and the second drive gear 94 are disengaged from clutch collar 96.

A ball poppet means for axially positioning the clutch collar 96 with respect to the drive shaft 38 is also provided and is best shown in Figures l and 5. Referring to Figure 5, a plurality of radially extending cylindrical bores |28 are provided in countershaft 38. These bores |28 are located in alternate crotches between the splines. The ball poppet means further comprises a compression spring |30 positioned in each bore |28, and a steel ball |32 mounted in each bore |28 adjacent the mouth thereof. These balls |32 are in engagement with the spring |30 in the bore |28, and are resiliently biased outwardly from bore |28.

The clutch collar 98 is provided with a plurality of arcuate grooves |34 located in the faces of the splines of the clutch collar 96. These arcuate grooves lie in planes perpendicular to the longitudinal axis of the clutch collar 36 and the countershaft 38, and are adapted to receive the resiliently biased balls |32, whereby resistance to axial displacement by the clutch collar 86 and the countershaft 38 is obtained. As shown in Figure l, these arcuate grooves |34 are provided in three planes to provide for the three positions of the clutch collar; the first position, as shown in Figure l, being with the gear |20 in mesh with splined recess |24, the second position being with gear |20 positioned in recess |26, and the third position being with gear |28 in mesh with splined recess |22.

The mechanism for sluiting the clutch collar 96 includes a bracket generally indicated at |36, best shown in Figures 2, 3 and l1. The bracket |36 has a cap portion |38 which is split so that the cap |38 may be adjustably clamped on the extended end 49 of reverse gear shaft 48, by means of bolt |40. The bracket |36 has extending from the cap portion |38 an arm |42 which has drilled therein a vertical bore |44 adapted to receive a rotatable member. Also extending from arm |42 is a collar |46 which is coaxially positioned around the clutch collar 96. The collar |46 is spaced from the surface of clutch collar 96, so as to provide clearance between the two coaxial members.

It can be seen that by rotating the control arm |86, the linkage carries the motion through the rock shaft |68 through the linkages to the control arms |48. 'I'he arms |48 and |50 are swung through an arc, by means of rock shaft I! which is pivoted within bore |44, to effectuate shifting of the clutch collar 96.

A means for axially positioning the driven. gears 88 and 94 with respect to the countershaft 38 is also provided, as shown in Figurey 1. A ring |94 is positioned between bearing 98 and shoulder |86 on countershaft 38. This ring |84 positions the bearing 90 with respect to motion to the left. A snap ring |88 is mounted in an inner recess in first driven gear 88 and engages the bearing 86. The rst driven gear 88 and second driven gear 94 have a bearing interface 200 therebetween.. In order to restrict the mot.. on of second driven gear 94 in the direction to the right, as seen in Fi.,- ure 1, a pair of spacer rings 202 and 264 are provided on opposite sides of collar I 46, with the spacer ring 204 being inserted in a recess in double gear |02, which gear |62 is fixed axially relative to countershaft 38 in the manner described above. It can be seen that the ring |94 and shoulder |96 cooperating with snap ring |88, spacer rings 202 and 204, collar |46 and double gear |82 together clamp the driven gears 88 and 84 in substantially non-movable positions axially, while driven gears 88 and 94 remain rotatably mounted with respect to countershaft 38.

In the form of the invention shown in Figure i, the extension shaft I6 is provided with a double gear I4. One of the gears I2 of double gear I4 constitutes the first power drive gear. The second power drive gear 'I2 is splined to the first power drive gear, but is rotatably mounted on a reduced portion of the drive shaft 255. A second gear I3 of the double gear I4, integral with the extension shaft I6, retains its previous function of driving some member which is not a necessary part of this invention.

In the form of the invention shown in Figure 12, this second gear I3 of the double gear I4 is used as the second power drive gear. .Also shown in ligure'lI is another arrangement of the use of spacers and snap rings to keep the driven gears in fixed axial position with respect to the drive gears.

Referring now more specifically to Figure 12, the extension shaft I6 is journalled in the wall 20 by means of bearing I8. As described above, the extended end of drive shaft 26 is supported `by means of bearing 24 within recess 22 at the end of extension shaft I8. The first power drive gear I2 is reduced in diameter over a portion of the gear edge thereof as indicated at 56. This reduced portion of the rst power drive gear I2 is 'adapted to mesh with internal dental elements 220 formed in the second single shiftable gear 66.

The gear 66, with the internal dental elements 220, is the same as that supplied in the unmodied transmission of the manufacturer. It is a primary purpose in this modified form to use as many of the original parts as possible to obtain the same end results.

The first power drive gear I2 is in mesh with a driven gear 222 and the second power drive gear I3 is in mesh with a second driven gear 224. These driven gears 222 and 224 are mounted with respect to the countershaft 38 in the same manner as the

respective gears

94 and 88 shown in Figure 1, except for minor mechanical variations.

It is pointed out, however, that gear 94 in Figure 1 was in mesh with the second power drive gear and was rotatably mounted on the clutch collar 86, while gear 222 is in mesh with the rst power drive gear and is rotatably mounted on the clutch Collar 9S.

To eliminate any possible axial movement of the driven gears with respect to the countershaft 38, an arrangement of spacers and snap rings is provided. The gear 224 is shown rotatably mounted on countershaft 38 by means of bearings 226 and 228. A snap ring 230 is mounted on countershaft 38 and restrains spacer 232 which engages the lower race of bearing 226. A spacer 234 is provided between the lower races of bearings 226 and 228 and the lower race of bearing 228 butts against a shoulder 236 formed in countershaft 38. A snap ring 238 is positioned in a recess in gear 224 and engages the upper races of bearings 226 and 22S. The bearings 226 and 228 are restrained from axial movement along countershaft 38 by means of the snap ring 230, the spacers 232 and 234, and the shoulder 236. The snap ring 238 restrains the gear 224 from movement axially on the outer races of the bearings 226 and 228.

The

gears

222 and 224 have a butting interface 240 therebetween. This prevents movement of the gear 222 axially to the left, as shown in Figure 12, on countershaft 38. The gear 222 is rotatably mounted on bearing 88 which is concentrically mounted on clutch collar 96. To prevent any movement of the gear 222, axially to the right with respect to countershaft 38, there is provided a spacer 242, a collar |46, and a second spacer 244.

As was described above, the double gear |02 is restrained from axial movement on countershaft 38 by means of snap rings |04. The spacer 242 also engages the bearing 98 and prevents movement thereof to the right. The spacer 244 is of a size sufficient to accommodate any space between the collar I 46 and the recessed face of double gear |02.

In the form of my invention shown in Figure 13, the second power drive gear is also mounted on the extension shaft I6, but is separate from the second gear I3 of the double gear I4 so that the original use of the gear I3 may still be retained. It has also been found that the size of the second driven gear is somewhat restricted by the shape of the transmission housing when the second driven gear is in mesh with the gear I3, as shown in Figure 12. This is because there are certain faired surfaces in the interior of the transmission housing which interfere with driven gears of larger diameter. But by moving the second driven gear further away from the Wall 20 of the transmission housing I8, these faired surfaces are avoided, permitting the use of larger gears.

It is, therefore, the purpose in this modification to provide a second driven gear which could be positioned further away from the wall 20 of the transmission housing I0, thereby permitting use of more desirable gear ratios. Accordingly, the extension shaft I6 is modified so that only the rst power drive gear I2 is integral therewith. A second power drive gear 300 is keyed to extension shaft I6 by means of key 302. A gear 304 corresponding to gear I3, as shown in Figures 1 and 12, is also provided and it, too, is keyed by means of key 302 to extension shaft I6. This gear 384 performs the same function as gear I3. A first driven gear 306 is in mesh' with first power drive gear l2 and the second driven gear 308 is in mesh with second power drive gear 380.

The type of bearing support for the extension shaft I8 is more elaborate in Figure i3 than is shown in Figures 1 and 12, and includes a bearing cage 3H) which is bolted, by means of bolts 312, to the wall 20 of the transmission housing l0. This bearing cage 3l8 has a pair of bearings 3I4 and 3l6 mounted therein. I'he outer races of the bearings 3|4 and 3l6 are restrained in the cage 3 I 8 by means of snap rings 3I8 and 320 and by means of shoulders 322 and 324. A spacer 32S,

i concentric with extension shaft I6, is provided thereof. Similar axially extending hub portions on driven gears 305 and 308 butt against each other to form an interface 338 which prevents engagement by the gear face of first driven gear 300 with hub portions of the first driven gear 383 during rotation thereof.

The axial positioning of the driven gears 303 and 308 to prevent axial movement thereof with respect to the countershaft 38 includes a bearing cage 332 which fixes the bearing 40 with respect to the wall 20. A spacer 334, concentric with countershaft 38, engages the inner race of bearing 40 and the hub portion 338 of second driven gear 308. The hub portion 336 is restrained from moving to the left by spacer 334, and is restrained from moving to the right by shoulder 338 in countershaft 38. A sleeve bearing 340 is provided for the second driven gear 308 and has a stepped portion which engages shoulder 342 in countershaft 38. The bearing 340 is restrained from movement to the left by spacer 334 and by movement to the right by shoulder 342.

The first driven gear 386 is restrained from axial movement to the left with respect to countershaft 38 by the butting interface 330. A semicircular ring 344 which is integral with bracket 38 engages the face of gear 308 to restrict movement of gear 306 toward the right. This semicircular ring 344 is positioned concentric with the hub portion 343 of gear 305. In the modified form shown in Figure 13, the collar M6 shown in Figures 1 and l2 has been eliminated as the semicircular ring 344 performs the same function of restraining movement of the driven gear axially to the right. The bracket |36 is mounted on the extended end 49 of reverse gear shaft 48, as described hereinabove.

Operation In the operation of the transmission and overdrive, the first and second power drive gears are always in mesh and rotate as a unit. The first driven gear 88 and second driven gear 94 are in mesh respectively with first power drive gear I2 and second power drive gear 'i2 and hence are always rotated. When the clutch collar 96 is in the position shown in Figure l, the first driven gear 88 is not rotating as fast as is the second driven gear 94. In the position shown in Figure 1, the second driven gear 04 is splined through clutch collar 96 to countershaft 38, and the countershaft rotates with second driven gear 94. At that time the first driven gear 88 is underrunning the countershaft 38. To provide the various speeds for the tractor or vehicle, the transmission gears 58, 30 and 66 are shifted as before and provide for different speeds.

When the clutch collar 98 is in the position shown in Figure 9, then the first driven gear 88 is splined in driving connection to the countershaft 38 and the second driven gear 94 is overrunning with respect to the countershaft 38. The bearing surface 98 between the clutch collar 98 and the second driven gear 94 provides for ease of rotation. When in this position with the first driven gear in driving connection with the countershaft 38, there are still four more speeds available by shifting the gears 58, 80 and 86, into engagement with the gears mounted on and rotating with countershaft 38.

When the clutch collar is positioned so that gear 120 is within the recess |26, then neither the first driven gear nor second driven gear are in driving engagement with the countershaft 38 and hence countershaft 38 does not rotate. At that point, only one speed is available for the wheels of the tractor and that is obtained by shifting gear 88 in the direction where the internal splines 84 in gear 88 may engage the recessed gear edge 82 of second power drive gear 12. In fact, even if the clutch collar 96 is in engagement with either of the two driven

gears

88 or 94, this speed resulting from the engagement of recessed gear edge 32 with internal splines 84 of gear 35 is always available.

Thus, it can be seen that I have provided a novel overdrive system for a motor vehicle, which overdrive system may be easily fitted into the existing transmission housing and adapted to the existing transmission system therein, and which overdrive system preserves all the original speeds of the transmission besides providing a range of higher speeds, whereby for example an existing five speed transmission is converted into a nine speed transmission.

There have also been provided a simple and inexpensive shifting means, a novel support bracket for the shifting means adapted to be mounted within the transmission housing, and ball poppet means for positioning shiftable coaxial overdrive members with respect to each other in a plurality of predetermined positions.

While there has been shown and described a particular embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and, therefore, it is intended in the appended claims to cover all such changes and modications as fall within the tru-e spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An overdrive gear system comprising first and second power drive gears rotating as a unit, a shaft, a first and a second driven gears rotatably mounted coaxially with said shaft and respectively in mesh with said first and said second pbwer drive gears, means including an axially shiftable clutch collar splined to said shaft for selectively connecting said first or second driven gears in driving relation to said shaft, one of said driven gears being rotatably mounted on said clutch collar, and a sleeve surrounding said clutch collar and restricting axial motion of the driven gears with respect to said shaft, said sleeve 13 having apertures therein through which shifting elements are adapted to extend to engage the clutch collar for shifting said clutch collar.

2. An overdrive gear system comprising iirst and second power drive gears rotating as a unit, a shaft, a rst and a second driven gears rotatably mounted coaxially with said shaft and respectively in mesh with said rst and said second power drive gears, means including an axially shiftable clutch collar splined to said shaft for selectively connecting said rst or second driven gears in driving relation to said shaft, a transmission gear splined to said shaft and rotatable therewith, and a sleeve surrounding said clutch collar acting as a spacer between said transmission gear and the driven gear rotatably mounted on the clutch collar for restricting axial motion of said driven gear with respect to said' shaft.

3. An overdrive gear system comprising first and second power drive gears rotating as a unit, a shaft, rst and second driven gears rotatably mounted coaxially with said shaft and respectively in mesh with said first and second power drive gears, means including an axially shiftable clutch collar splined to said shaft for selectively connecting said first or second driven gears in driving relation to said shaft, one of said driven gears being rotatably mounted on said clutch collar, a stop member concentric with said clutch collar engaging the driven gear rotatably mounted on said clutch collar to restrict axial movement of said driven gear, a mounting bracket for said stop member adapted to nx said stop member axially in position, and means mounted on said bracket for shifting said clutch collar.

4. An overdrive gear system comprising first and second power drive gears rotating as a unit, a shaft, rst and second driven gears rotatably mounted coaxially with said shaft and respectively in mesh with said first and second power drive gears, means including` an axially shiftable clutch collar splined to said shaft for selectively connecting said rst or second driven gears in driving relation to said shaft, one of said driven gears being rotatably mounted on said clutch collar, means including a stop member concentric with said clutch collar for engaging the driven gear rotatably mounted on said clutch collar to restrict axial movement of said driven gear, a mounting bracket for said stop member adapted to x said stop member axially in position, said stop member having elongated apertures therein, and means mounted on said bracket for shifting said clutch collar, said means including shifting elements extending through the apertures in said stop member and engaging said clutch collar.

5. An overdrive gear system as set forth in claim 3 wherein said stop member is axially coextensive with only a portion of said clutch collar, and wherein said means for shifting said clutch collar includes shifting elements spaced axially from said stop member and engaging said clutch collar.

References Cited in the iile of this patent UNITED STATES PATENTS Number Name Date 2,115,390 Lasley Apr. 26, 1938 2,241,002 Peterson May 6, 1941 2,464,479 Avila Mar. 15, 1949