REVERSIBLE POWER TRANSMISSION

Abstract: A reversible power transmission having input and output main shafts (2, 4) comprises a first gear wheel (6) nonrotatably connected with one of the two main shafts, a second gear wheel (7) disposed on an intermediate shaft (8) having also axially spaced-apart third and fourth gear wheels (12, 13), of which the latter (13) is larger than the former (12), and being rotatably mounted in relation to a cover (9) which is rotatable about the same geometrical centre axis as are the two main shafts (2, 4). The third gear wheel (12) engages a fifth gear wheel (14) which is nonrotatably connected with the second main shaft (4). The fourth gear wheel (13) engages a sixth gear wheel (15) which is disposed on a brakable sleeve (16) mounted on the outside of the second main shaft (4), the input main shaft (2) being drivable at all times in one and the same direction of rotation, while the output shaft (4) is drivable in one of two opposite directions of rotation by braking of either the cover (9) or the sleeve (16). If neither the cover nor the sleeve is braked, the transmision will be disengaged and no power transmitted at all.

Description: REVERSIBLE POWER TRANSMISSION Background of the invention When power is to be transmitted from a power source to rotary processing means in disintegrators of the type adapted to disintegrate heavy material, such as construc¬ tion waste, hard wood or pieces of concrete, there is need of a power transmission capable not only of transmitting considerable driving torques during normal operation, but also of being reversed in case the processing means of the machine are jammed by exceptionally hard objects, e.g. steel girders and the like, accompanying the material to be disintegrated. For this purpose, hydraulic type trans¬ missions have previously been used, but these are com- plicated, expensive to manufacture and, furthermore, has poor efficiency. Another disadvantage of these transmis¬ sions is that they cannot withstand heavy loads during start-ups. Summary of the invention The present invention aims at providing a reversible power transmission having input and output main shafts and being especially, but not solely, adapted to be used in disintegrators. This power transmission should be made up of simple mechanical components and thus be inexpensive to manufacture as well as reliable and highly efficient in operation. According to the invention, this is achieved in that the transmission comprises a first gear wheel nonro¬ tatably connected with one of said two main shafts, a se¬ cond gear wheel disposed on an intermediate shaft having also axially spaced-apart third and fourth gear wheels, of which the latter is larger than the former, and being ro- tatably mounted in relation to a cover or member which is rotatable about the same geometrical centre axis- as are the two main shafts; that the third gear wheel engages a fifth gear wheel which is nonrotatably connected with the second main shaft; and that the fourth gear wheel engages a sixth gear wheel disposed on a brakable sleeve mounted on the outside of the second main shaft, the input main shaft being drivable at all times in one and the same di¬ rection of rotation, and the transmission being arranged a) to drive, in an operating state, the output main shaft in the same direction of rotation as the in¬ put shaft by maintaining the cover in braked con¬ dition and the sleeve in freely rotatable condi¬ tion, the power transmission between the main shafts taking place via the first, second, third and fifth gear wheels; b) to drive, in a reversing state, the output main shaft in a direction of rotation opposite to that of the input shaft by maintaining the sleeve in braked condition and the cover in freely rotatable condition, the power transmission between the main shafts taking place via the intermediate shaft which, by its own rotation and the simultaneous engagement between the fourth and the sixth gear wheels, causes the cover to rotate, in a direction opposite to the direction of rotation of the input main shaft, the engagement between the third and the fifth gear wheels causing the intermediate ' ' shaft to bring along the output shaft in the same direction of rotation as the cover, in consequence of the fourth gear wheel being larger than the third gear wheel; and c) to transmit, in a state of disengagement when the cover and the sleeve both are freely rotatable, no power at all between the main shafts. Brief description of the drawings In the drawings, FIG. 1 is a longitudinal section schematically showing the transmission according to the invention in an operating state, i.e. the normal state of operation, FIG. 2 is a schematic perspective view showing the transmission in the state in Fig. 1, FIGS. 3 and 4 are a longitudinal section and a perspec¬ tive view, respectively, showing the trans¬ mission in a state of reversion, FIGS. 5 and 6 are a longitudinal section and a perspec- tive view, respectively, showing the trans¬ mission in off-position, FIG. 7 is a schematic view of an arrangement for automatic disengagement of the transmission in the event of overloading, and FIG. 8 is an end view of the arrangement in Fig. 7. Description of a preferred embodiment In Fig. 1, a power source 1 is connected , via a first main shaft 2, with a transmission according to the invention, in its entirety designated 3. A second main shaft 4 is connected with a rotatable member 5, e.g. a cy¬ linder or screw belonging to a disintegrator and equipped with processing means. In the shown embodiment, the main shaft 2 forms an input or driving shaft, whereas the main shaft 4 forms an output or driven shaft. In actual prac- tice, the input shaft 2 may be a cardan shaft, but it is also possible to connect the power source 1 with the transmission 3 by means of a rigid shaft. The transmission according to the invention comprises a first gear wheel 6 which is nonrotatably connected with the input shaft 2 and which engages a second gear wheel 7 disposed on an intermediate shaft 8 which is rotatably mounted in relation to a cover or member 9. In its turn, this cover is, via bearings 10, 11, rotatably mounted about one and the same geometrical centre axis as are the two main shafts 2, 4. To be precise, the two opposite ends of the intermediate shaft 8 are mounted in two spaced- apart end walls 9', 9" of the cover 9. Furthermore, axial¬ ly spaced-apart third and fourth gear wheels 12, 13, of which the latter has a larger diameter and more cogs than the former, are nonrotatably connected with the interme¬ diate shaft 8. The third gear wheel 12 engages a fifth gear wheel 14 which is nonrotatably connected with the output shaft 4, and the fourth gear wheel 13 engages a sixth gear wheel 15 disposed on a brakable sleeve 16 mounted on the outside of the output shaft 4. In this pre¬ ferred embodiment, the sleeve 16 is connected with, or made in the same piece as, a balance wheel 17 having con¬ siderable mass. The cover 9 comprises an annular flange 18 adapted to cooperate with a first braking device 19, and in analogous manner, the balance wheel 17 is adapted to cooperate with a second braking device 20. In actual practice, the cover 9 may be sealed outwards and contain a lubricant, such as oil, for lubricating the gear wheels within. Each braking device 19, 20 comprises a pair of brake shoes 19', 19" and 20', 20", respectively, each of which is movable towards and away from the flange 18 and the ba¬ lance wheel 17, respectively. More precisely, the brake shoes are mounted on bodies 21, 22 which are pivotable about the same pivot shaft 23. As is apparent from Figs. 7 and 8, each body 21, 22 is connected with a hydraulic cy- under 24, 25 whose working chamber is connected with the same hydraulic system which supplies the brake shoes 19 ' , 19" and 20', 20" with hydraulic liquid. This hydraulic system comprises two sublines 27 and 28 connected to a common control valve 26 and alternately serving as supply line or return line. The subline 27 has a branch line 27' to the cylinder 24, and two branch lines 27" to the two brake shoes 19', 19". In analogous manner, the subline 28 has a branch line 28' to the cylinder 25, and two branch lines 28" to the brake shoes 20', 20". The hydraulic sys- tern also comprises a pump 29, a tank 30, and a pressure relief valve 31. The control valve 26 is adjustable by means of magnetic devices 32, 33 which are electrically connected to sensors 34 and 35, respectively, adapted to sense, possible pivoting movements of the bodies 21, 22 in relation to the pivot shaft 23. Assuming that the cover 9 is to be maintained braked, while the balance wheel 17 is freely rotatable, the con¬ trol valve 26 is adjusted such that the pump 29 supplies hydraulic liquid to the cylinder 24 and the brake shoes 19', 19" via the subline 27, the subline 28 serving as a depressurised return line. The brake shoes 19', 19" are now applied against the flange 18 of the cover 9, and the cylinder 24 maintains the body 21 in a normal operating state. If there should be a tendency of the transmission 3 being overloaded, e.g. due to the presence of exceptional¬ ly resistant objects among the material processed in the disintegrator, the body 21 strives to pivot out of its initial position. This pivoting movement causes the sensor 34 to impulse the control valve 26 to be set to the neu- tral position shown in Fig. 7, in which there is no pres¬ sure in the subline 27. Figs. 1 and 2 show the transmission in an operating state. The power source 1 operates at all times with one and same direction of rotation of the input shaft 2. In the operating state shown in Figs. 1 and 2, the cover 9 is maintained braked, while the balance wheel 17, or more precisely the sleeve 16, is maintained freely rotatable. Since the cover 9 and, consequently, also the intermediate shaft 8 are stationary, the power transmission between the input shaft 2 and the output shaft 4 will be carried out via the first, second, third and fifth gear wheels 6, 7, 12 and 14, of which the latter is directly nonrotatably connected with the output shaft 4. In the operating state in Figs. 1 and 2, the output shaft 4 is thus driven in the same direction of rotation as the input shaft 2. The transmission ratio can be varied by changing the size of the above gear wheels. In Figs. 3 and 4, the transmission is shown in a re¬ versing state, in which the balance wheel 17 is maintained braked, while the cover 9 is freely rotatable. Due to the balance wheel 17 being stationary, also the gear wheel 15 nonrotatably connected with the sleeve 16 is maintained stationary. The input shaft 2 still drives the first gear wheel 16 in the same direction of rotation as in Figs. 1 and 2, as well as the second gear wheel 7 and the interme¬ diate shaft 8 nonrotatably connected therewith. Since also the third and fourth gear wheels are nonrotatably connect¬ ed with the intermediate shaft 8, the rotation of said shaft will make the shaft travel, due to the engagement between the fourth and the sixth gear wheels 13, 15, back¬ wards along the stationary sixth gear wheel 15, while bringing along the cover 9 which thus is caused to rotate in the opposite direction to that of the input shaft 2. Since the circumference of the fourth gear wheel 13 at the pitch circle is larger than that of the third gear wheel 12, the fourth gear wheel 13 will, when rolling on the sixth gear wheel 15, bring along the third gear wheel 12 an equal distance, but, due to its smaller circumference, the third gear wheel 12 will bring along the output shaft 4 a distance equalling the difference in circumference be¬ tween the fourth gear wheel 13 and the third gear wheel 12, although in a direction of rotation opposite to that of the input shaft 2, as made clear in Fig. 4. This re¬ versed driving of the output shaft is carried out with a number of revolutions lower than the normal operating num¬ ber of revolutions of the output shaft according to Figs. 1 and 2. In reversion, a desirable reduction of the number of revolutions is thus obtained for disintegrators. Figs. 5 and 6 show how the two braking devices 19, 20 are disengaged such that both the cover 9 and the balance wheel 17 are freely rotatable. In this case, there is no power transmission at all between the input shaft and the output shaft. It should be pointed out that the disengaging func¬ tion* shown in Figs. 7 and 8 can be achieved both in the operating state-in Figs. 1 and 2 and in the reversing state in"Figs. 3 and 4. In the former case, the sensor 34 senses a possible pivoting movement of the body 21, while in the reversing state, the sensor 35 senses possible pi- voting movements of the body 22. It should also be made clear that the hydraulic cylinder 25 associated with the body 22 is located behind said body and thus cannot be seen from in front of said body. It goes without saying that the invention is not re¬ stricted to the embodiment described above and shown in the drawings. Thus, it is for example conceivable to com¬ pletely dispense with the balance wheel, although such a wheel is preferred in connection with transmissions for hard-working disintegrators. If there is no balance wheel, only the sleeve connected with the sixth gear wheel can be brakable, e.g. by means of a simple brake shoe. Although the main shaft 2 has, in the embodiment shown, been desig¬ nated as a driving input shaft, while the main shaft 4 has been designated as a driven output shaft, it may naturally be the other way around. Furthermore, it should be pointed out that the two braking devices may be constructed in many different ways and comprise, for example, only one movable brake shoe each, adapted to cooperate with a fixed brake lining. Also, the braking devices may use some other pressure medium than hydraulic oil.

Claims: CLAIMS 1. A reversible power transmission having input and output main shafts (2, 4), c h a r a c t e r i s e d in that it comprises a first gear wheel (6) nonrotatably con¬ nected with one (2) of said two main shafts (2, 4), a se¬ cond gear wheel (7) disposed on an intermediate shaft (8) having also axially spaced-apart third and fourth gear wheels (12, 13), of which the latter is larger than the former, and being rotatably mounted in relation to a cover or member (9) which is rotatable about the same geometri¬ cal centre axis as are the two main shafts (2, 4); that the third gear wheel (12) engages a fifth gear wheel (14) which is nonrotatably connected with the second main shaft (4); and that the fourth gear wheel (13) engages a sixth gear wheel (15) disposed on a brakable sleeve (16) mounted on the outside of the second main shaft (4), the input main shaft being drivable at all times in one and the same direction of rotation, and the transmission being arranged a) to drive, in an operating state, the output main shaft (4) in the same direction of rotation as the input shaft (2) by maintaining the cover (9) in braked condition and the sleeve (16) in freely rotatable condition, the power transmission be¬ tween the main shafts (2, 4) taking place via the first, second, third and fifth gear wheels (6, 7, 12, 14); b) to drive, in a reversing state, the output main shaft (4) in a direction of rotation opposite to that of the input shaft (2) by maintaining the sleeve (16) in braked condition and the cover (9) in freely rotatable condition, the power transmis¬ sion between the main shafts taking place via the intermediate shaft (8) which, by its own rotation and the simultaneous engagement between the fourth and the sixth gear wheels (13, 15), causes the co- ver to rotate, in a direction opposite to the di¬ rection of rotation of the input shaft, the en¬ gagement between the third and the fifth gear wheels (12, 14) causing the intermediate shaft to bring along the output shaft in the same direction as the cover, in consequence of the fourth gear wheel (13) being larger than the third gear wheel (12); and c) to transmit, in a state of disengagement when the cover (9) and the sleeve (16) both are freely ro¬ tatable, no power at all between the main shafts. 2. Transmission as claimed in claim 1, c h a r a c ¬ t e r i s e d in that the intermediate shaft (8) is sup¬ ported by and rotatably mounted in two end walls (9', 9") of the cover (9), which are separate from one another. 3. Transmission as claimed in claim 1 or 2, c h a ¬ r a c t e r i s e d in that all the gear wheels (6, 7, 12, 13, 14, 15) are contained in the cover (9) which is sealed outwards and holds a lubricant for the gear wheels. 4. Transmission as claimed in any one of the preced¬ ing claims, c h a r a c t e r i s e d in that an annular flange (18) adapted to cooperate with a braking device (19) is associated with the cover (9). 5. Transmission as claimed in any one of the preced- ing claims, c h a r a c t e r i s e d in that a balance wheel (17) is non-rotatably connected with the sleeve (16) associated with the sixth gear wheel (15). 6. Transmission as claimed in any one of the preced¬ ing claims, c h a r a c t e r i s e d in that the sleeve (16) and/or the balance wheel (15) are adapted to coope¬ rate with a second braking device (20). 7. Transmission as claimed in claims 4 and 6, c h a r a c t e r i s e d in that the individual braking device (19, 20) comprises at least one brake shoe (19', 19"; 20', 20") which is movable back and forth between ac¬ tive and inactive positions and which is mounted on a body (21, 22) adapted to turn about a pivot shaft (23) and con- nected with a compressed-fluid cylinder (24, 25) whose working chamber is connected with one and the same com¬ pressed-fluid system which supplies the brake shoe with compressed fluid, and that the compressed-fluid system comprises two sublines for the two braking devices (19, 20), connected with the same control valve (26), a sensor (34, 35) adjacent to the body (21, 22) of the individual braking device being adapted to sense any pivoting move¬ ments of the body that may occur from an intial position, and impulse the hand valve (26) to cut off the supply of compressed fluid to the braking device at issue, so as to interrupt the braking effect thereof on the cover flange and the sleeve, respectively.

Inventors: NYBERG JAN-ERIK, NYBERG, JAN-ERIK
Applicants: NYBERG JAN ERIK, NYBERG, JAN-ERIK
Application year: 1990
Main classification: F16H3
IPC codes: F16H3