SYSTEM AND METHOD TO PREVENT THE JUMP
OF ENGRANE IN A COMPOSITE TRANSMISSION
Technical Field The present invention relates to composite transmissions of vehicles, and more particularly to a system for preventing gear jumping during a power take-off (PTO) operation in a composite transmission. Background Art Compound gear shift transmissions are typically associated with heavy duty vehicles such as large trucks, tractors / semi-trailers, and the like. Composite transmissions comprise main and auxiliary transmission sections connected in series, and provide a total number of available transmission relations equal to the product of the relations of the main and auxiliary sections. By way of example, a gear shift composite transmission comprising a four (4) speed main section, connected in series with an auxiliary section of four (4) speeds, will provide sixteen (4x4 = 16) available ratios. The power is transmitted from the motor, through the master clutch and towards the transmission, via the input arrow. In Fuller transmissions, a gear to the input shaft (namely, the gear of the head assembly) meshing permanently with two counter-gear gears positioned 180 ° away at the gear periphery of the head assembly is muted. The torsion is transmitted to the countershaft gears and later through the countershafts. The countershafts generally include several gears that mate with main arrow gears that are positioned along the same axis of the input shaft, free to float on a floating main shaft. Clutches are provided between the main shaft and the main shaft gears to provide progressive ratios. By moving a clutch from its neutral position to a linked position, torque is transmitted from the countershafts to the main arrow gear, through the clutch and to the main arrow. This method divides the input torque equally between the countershafts and brings the torque geared back to the main shaft gear, again divided equally. In order for the torsion to be divided equally and effectively, it is important that the main shaft, the main shaft gears and the clutches are capable of floating to assume centered positions. It is not necessary to firmly fix the main arrow and main arrow gears, as is common practice with single-arrow transmissions placed, as the separation and tangential forces generated in the gear teeth are equal and opposite and therefore cancel out each. In fact, fixing the main arrow / input arrow gears can be harmful and produce a torsion imbalance because it is impossible to manufacture the gear train perfectly, ie at absolute sizes without tolerances. Manufacturing tolerances can result in the gear teeth of the main-arrow and input-shaft gears being loaded more heavily on one side than the other, and consequently the gears on one counter-shaft are loaded more than on the other side. other. Furthermore, this can give rise to problems of gear knocking and, in extreme cases, gear jump during normal driving conditions. In a medium working transmission, with a single arrow positioned, the torque is supplied to the transmission via the input shaft through the gear of the head assembly, and the gear of the head assembly is passed to an arrow gear set to torque , and towards the unique placed arrow. In this case, the main shaft is simply supported with bearings with very little free radial space. The main shaft gears are kept concentric with the main shaft in needle bearing bearings. This is necessary due to the high tangential and separation forces established between the two mating gears, which must be reacted by rolling elements to the transmission housing. Compound transmissions are sometimes used for power take-off (PTO) operation in which the torque is transmitted from one of the countershafts to an auxiliary unit, such as a pump or flange device to operate a truck platform hoist , etc. The gear of the head assembly of a conventional twin counterflexer Fuller transmission is muted to the input shaft with a small diametral float, and when a power take-off device is used to drive from the front countershaft, the transmission is used in a form of a single arrow placed. The gear of the head assembly or the main arrow gears are not coupled to the main shaft, and therefore there is no torsional division. The gear of the head assembly drives the torsion through only one counter-shaft. As the gear of the head assembly is not engaged with the clutch, there can be no gear jump. The small free diametral space ensures that the gear of the head assembly runs concentric with the input shaft and that the large traction notches are strong enough to sustain load cycles during PTO operation. In certain designs, the divider is configured such that the gear of the head assembly, which is usually mounted on the input shaft via a notch, may be free to rotate and float, and perform the function of low division (in an overdrive transmission) as well as the function of the fourth gear. This gear is mounted on a spindle that is screwed to the main shaft. The gear bore of the head assembly includes a clearance adjustment for the spindle so that it can float under normal operating operation to ensure a balanced torsional division. It is also supported axially by cylindrical thrust bearings that compensate for the apparent thrust forces during normal operation due to the helical gear, which is not balanced. These forces are accompanied by a differential rotation between the gear of the head assembly and the spindle when the low-division gear is selected (ie, when it is an impulse gear), hence the need for thrust bearings. A divider gear is then placed on the input shaft, forward of the gear of the head / fourth gear assembly, with a gap of clearance in the input shaft which provides a high division function. These two gears are then selectable using a splitter clutch which is locked to the input shaft and are free to slide along the notch to provide the clutch function. This design is operational for normal driving conditions; however, when these two gears are used for PTO operation, there is a tendency for the clutch to jump out of engagement. In essence, the reason for this jump condition, both at high and low division, is due to the fact that the transmission is being used as a single-arrow transmission placed without bearings under the impulse gear. The jump can be attributed to inadequate parallelism and concentricity between the selected divider or the gear of the head assembly, the splitter clutch and the arrow on which the gear is placed. The gear becomes radially displaced, taking up the clearance between the gear hole and the arrow in the high-division position, and similarly in the low-division position, but with the added clearance that exists due to the floating nature of the gear. Main arrow and the spindle. This results in a knocking effect. There is a need to provide such torsion division options, while the availability of PTO operation corresponding to both the splitting gear and the meshing of the head / fourth gear assembly is also provided. It is necessary to provide gear flotation for balanced torsional division; however, unfortunately, this buoyancy allows greater engagement bumping, particularly during PTO operation, which increases the possibility of gear jump in the splitter clutch. It is desirable to provide a composite transmission design that provides substantially balanced torsional division, with the availability of PTO operation corresponding to both the splitting gear and the gear head / fourth gear engagement without increasing the risk of gear jump during PTO operation. SUMMARY OF THE INVENTION The present invention overcomes the aforementioned limitations of prior art composite transmission assemblies by providing a composite transmission that includes a divider gear rotatably mounted on an inlet shaft and a gearhead / fourth gear assembly, both mounted on the entry arrow. The splitter gear is provided with a minimum diametrical float of 0.005 to 0.020 inches from the input shaft to minimize the pounding of the splitter gear while allowing for substantially balanced torsional division, and the gear head / fourth gear engagement is mounted on the input shaft via a pair of opposingly tapered bearing bearing assemblies, arranged around the input shaft to minimize tapping of the gear head / fourth gear engagement. In this way, the gear jump is prevented during PTO operation, and a substantially balanced torsional division is achieved. More specifically, the present invention provides an improved composite transmission with reduced gear hop, including an input shaft disposed along a central axis, a floating main shaft disposed substantially along the central axis adjacent to the input shaft, an auxiliary section adjacent to the main shaft, and at least one counter shaft parallel to and spaced from the central axis, said counter shaft being operative to transmit input shaft torque to the main shaft and to facilitate PTO operation. The assembly further comprises a divider gear disposed in the input shaft and includes a central bore formed therethrough with a minimum free diametral space of between 0.005 and 0.020 inches, with respect to the input shaft to minimize tapping of the splitter gear, and enough free diametral space for load sharing balance. A synchronizer is arranged around the input shaft adjacent to the divider gear and includes a clutch notch. A pair of opposing tapered bearing bearing assemblies are arranged around the input shaft, adjacent to the synchronizer. A head assembly gear is rotatably mounted on the pair of opposing tapered bearing assemblies to minimize the engagement knock during PTO operation. The synchronizing clutch notch is selectively engageable with a selected gear between the splitter gear and the head assembly gear, and the possibility of gear jump of any of the gears with respect to the clutch notch during PTO operation is reduced. A method of eliminating gear jump during PTO operation in a composite transmission set is also provided. The method comprises: (1) providing a divider gear in the input shaft with a minimum free diametral space with respect to the input shaft to minimize the splitting engagement knock; (2) providing a pair of bearing bearing assemblies tapered oppositely in the input shaft; and (3) mounting a head assembly gear on the pair of opposing tapered roller bearing assemblies to minimize knocking of the head assembly gear. Accordingly, an object of the present invention is to provide a composite transmission assembly with a substantially balanced torque splitting capability with available low division and high division operations while reducing the possibility of gear jump during PTO operation. The above object and other objects, aspects and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention, when taken in relation to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a vertical cross section of a composite transmission of Fuller shifts, of twin countershafts, of the prior art; Figure 2 shows a partial, amplified cross-sectional view of a composite transmission assembly according to the present invention; Figure 3 shows an amplified view in sections of the transmission shown in Figure 2; Figure 4 shows a sectional view, cut away, of a head assembly gear and gear according to the embodiment shown in Figure 2; Figure 5 shows a sectional view, partially cut away, amplified, of a sheave, head assembly and joint screw gear according to the embodiment shown in Figure 2; Figure 6 shows a sectional view, partly in section, amplified, of a sheave, gear head assembly and union screw according to the embodiment shown in Figure 2; and Figure 7 shows a plan view, in sections, cut away of the assembly shown in Figure 6. Detailed Description of the Preferred Embodiment Form Figure 1 shows a sectional view of a transmission assembly composed of twin countersail changes , Fuller, of the prior art 10. This typical twin countershaft assembly includes an input shaft 12 that carries torsion from the engine to the transmission. The input shaft 12 drives the gear of the head assembly 14, which is muted to the input shaft 12, and also permanently geared to opposite counter shaft gears 16. The counter shaft 18 includes a series of gears 20, 22, 24, 26 and 28 that mate with corresponding main arrow gears 21, 23, 25, 27 and 29 that are positioned along the same axis as the input shaft, free to float on a floating main shaft 30. The clutches are provided between the main arrow 30 and the main arrow gears to provide progressive relationships. The torsion is then transmitted from the main shaft through the auxiliary pulse gear 32, and towards the auxiliary section 34, and finally through the output shaft 36. The present invention, as shown in various embodiments in FIGS. FIGS. 2-7, provides such a composite transmission design with substantially balanced torsional division, while also providing the corresponding PTO operation availability with both the splitting gear and the meshing of the head / fourth gear assembly, without increasing the risk of skip gear during PTO operation. Referring to Figs. 2-3, a gear change composite transmission assembly 40 is shown in accordance with the present invention. The assembly 40 includes an input shaft 42 that carries torsion to the assembly. The input shaft 42 is supported within the transmission housing 44 by a spacer 46 which is supported rotatably with respect to the housing 44 by an input bearing 48, which is fastened to a sleeve 50.
The inlet arrow 42 is disposed along a central axis 52. A divider gear 54 is disposed in the inlet arrow 42 adjacent to the separator 46. The divider gear has a central bore 56 formed therethrough with minimal free diametral space of the order of 0.005 to 0.020 inches with respect to the input arrow in order to minimize the tapping of the splitter gear. This free diametral space provides sufficient buoyancy in order to maintain a substantially balanced division of torque between opposing counter-shafts when the splitting gear 54 is operated in a high-division mode. The minimum free diametral space provides approximately a range between 40-60 and 60-40% torsional division between opposing counterflections. This differential does not create a significant balance problem because the excess torsion in a counter-shaft causes the reaction of bearings and support structure in the assembly. In order to prevent further unbalance in the load sharing or torsion division unbalance, a sufficient free diametral space is maintained. Further back on the input shaft 42, a gear head / fourth assembly gear 58 is mounted on the input shaft 42 by means of a pair of oppositely tapered bearing bearing assemblies 60, 62, which are mounted on the entry arrow. These oppositely tapered bearing bearing assemblies 60, 62 minimize knocking of gear head / fourth gear engagement 58.
Accordingly, the present invention effectively minimizes the tapping of both the splitter gear 54 and the gear head / fourth gear gear 58 when operating in the high division or low division PTO operation mode, respectively, and the concentricity and the parallelism with respect to the clutch. Because the concentricity and parallelism of the splitter gear 54 and the gear head / fourth gear engagement 58 with respect to the clutch are maintained, these gears are less prone to slip out of engagement with the slide / clutch sleeve 78. Divider gear 54 or gear head / fourth gear engagement 58 can be selectively linked with the input shaft 42 by the beam ring synchronizer assembly 64. This type of beam ring synchronizer 64 is fully described in the US patent. United States No. 5,425,437, assigned to Eaton Corporation, incorporated herein by reference. Although this synchronizer is preferred, other synchronizer designs would be compatible with the present invention. The synchronizer 64 includes a fixed hub 66 secured to the notches 68 of the input shaft 42. Pre-energizing springs 70 pre-load the guide pins 72 and the rollers 74 against an annular groove 76 formed in the slide sleeve 78. Sliding sleeve 78 can slide through shift fork 80 via shift assembly 82 to selectively engage clutch 78 with either splitter gear 54 or gear head / fourth gear engagement 58. Gear splitter includes a synchro-flange 84 is moored thereto, which includes engaging teeth 86 that are engageable with the sliding clutch 78. Similarly, the gear head / quarter gear engagement 58 includes a synchro-flange 88, which is locked thereto and including engaging teeth. 90 which are similarly linkable with the sliding clutch 78. Synchro-rings 92, 94 are frictionally engageable with respective synchro-flanges 84, 88 in order to synchronize frictionally the rotational speed between the fixed hub 66 and the splitting gear 54 or the gear head / fourth gear engagement 58. The synchro-rings 92, 94 also act as blockers to prevent movement of the sliding sleeve / clutch 78 towards its respective synchro - tab 84, 88 until the respective synchro-flange 84, 88 is brought to the speed with the fixed hub 66 to allow engagement of the clutch 78 with the respective synchro-flange. The sliding movement of the sliding sleeve / clutch 78 is limited in the direction of gear engagement of head / fourth gear 58 by the sheave 96 and the fixed screw 98, as shown in Figures 2-6. On the whole, once the sleeve 78 is in place, the sheave 96 can be pushed onto the teeth 59 of the head assembly gear and indexed until the two radial holes 100 in the sheave 96 align with the two fixed screws 98, which are screwed into the fixed screw holes 102 formed in the gear head / fourth gear engagement 58. In this position, the notches 104 of the sheave 96 are in alignment with the meshing teeth 59 of the gear assembly. head / fourth gear 58 in order to act as a positive stop, as shown in figure 5. In this position, a suitable hexagonal key can be inserted through the radial access openings 106 formed in the sheave 96 so as to unscrew the fixed screw 98 until the fixed screw 98 seats in the screw seats 108 formed in the sheave 96. This configuration alleviates a problem found in many transmissions in which the screws They have a tendency to loosen themselves due to vibrations and with the presence of centrifugal force, to unscrew, and can enter the meshing teeth that mesh and cause damage. With this design, the fixed screws 98 must overcome the centrifugal force to screw themselves into gear 58, which is unlikely. Although the best mode for carrying out the invention has been described in detail, those skilled in the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.