Gear train assemblies

Gear train assemblies

DESCRIPTION
August 20, 1968 GE MOORE ASSEMBLIES gear train 5 sheets sheets 1 Filed April 28, 1967 Figure A.
August 20, 1968 G. E. MOORE GEAR TRAIN ASSEMBLY 5 Leaves -2 Sheet Filed April 28, 1967 20 , 1968 s . E. MOORE 3397589
Gearing ASSEMBLIES Filed April 28, 1967 5 Leaves leaves 5 ​​g I- 20 , GE MOORE 1968 3397589
Gearing ASSEMBLIES Filed April 28, 1967 5 Leaves leaves April 20, 1958 GE MOORE 3397589
Gearing ASSEMBLIES Filed April 28, 1967 5 Leaves leaves 5 ​​Inn { N726 fleas HM zit / c jfaa / e United States patent abstract description of a set of driving gears , driven gears and pulley, idler gear may move radially of the other gears , and the gears are cylindrical spacers to locate in mesh relatively accurate and is arranged so that during driving of the gears. a resultant driving force acting on the idler gear in a direction between the other gears to encourage and maintain the correct idle gear meshed with the other arts.
BACKGROUND OF THE INVENTION
(1) Field of the Invention This invention relates to gear train sets . I ( 2) Description of the Prior Art In some sets of known gear train which requires a gear wheel drive and a gear wheel driven to rotate in the same direction , a gear wheel is used to transmit intermediate driving unit to the driven sprocket. In such assemblies when driving and driven gear ratios are modified by replacement of one of the gear wheels with one of a pitch circle diameter different idler wheel then requires careful and accurate repositioning to properly position mesh with the driving and driven sprockets. As is known, the idler wheel is correctly engaged with each of the other wheels when your contacts gear pitch circle of the gear pitch circle each other in a point commontangential . It is found to be very difficult in practice to place the idler wheel in mesh with the driving and driven gear wheels and if the gears are located in positions that are incorrectly mesh , this situation can lead to more gear tooth wear faster and also the additional loading and increased gear bearings .

To avoid the above disadvantages , a set of gear train may be replaced by a sprocket assembly and which comprises a chain driven sprocket wheel and the driving sprocket that are rotated in the same direction by an endless chain located in driving engagement with the teeth of both gears , the chain is tensioned by a tensioning device in the chain. A set of gears and the chain is , however , more cumbersome than a set of gear train. A further disadvantage encountered when required to replace one of the sprockets is untension chain is necessary and then removed before the gear wheel is removable and after the replacement gear has been fitted , it is necessary to replace the chain and then re-tension .
SUMMARY OF THE INVENTION 

According to the present invention, a set of gear train comprises a driving and driven gear units , and a gear unit idler wheel operable to connect driving and driven units , the unit forwarding being movable radially with respect to at least one of the other units, and each unit comprises a sprocket and at least one coaxial cylindrical separator , the separator or each idler unit located in engagement with the spacers of the other units where the gear teeth of the forwarding unit are correct 3397589 patented August 20, 1968 " ice mesh with those of the other units, and the teeth properly mesh units , the provision units is such that when the drive unit is rotated in a direction to drive the driven unit , a resultant force of the driving forces applied to the teeth of the forwarding unit acts along a path between the centers of rotation of the other units so as to keep the teeth of the forwarding unit constantly correct mesh with the teeth of the other units .
It is clear to the applicants that the relative arrangement of the units is an important consideration in the invention. In practice, it is found that if all units have external gear teeth then the units must be relatively arranged so that when the teeth are in the correct mesh forwarding unit with the teeth of the other units, the angle produced between a line connecting the rotational centers forwarding unit and the drive unit and another line connecting the centers of rotation of the forwarding unit and driven unit is at least twice the pressure angle of the set. Furthermore, one of the driving and driven units can be an annular unit with internal gear teeth . In this case, the angle produced between a line joining the centers of rotation of the forwarding unit and driving do not cancel or driven unit and an extension of another line connecting the centers of rotation of the unit and the unit forwarding cancel is at least twice the pressure angle . Pressure angle term is used in its normal sense in the art accepted gear manufacturing .
Furthermore, the term correct mesh as mentioned above and throughout the specification indicates normal engagement of the teeth of the forwarding unit with each of the other units where the pitch circles of contact units in a single common tangent point .
According to another aspect of the invention, a gear assembly comprises a driving gear and driven gear units , the distance between the centers of rotation of the driving and driven units being variable , and a drive idler wheel operable to connect driving and driven units , the forwarding unit being movable radially with respect to at least one of the other units, and each unit comprises a sprocket and at least one coaxial cylindrical spacer , the or each separator unit forwarding ' lying in engagement with the spacers of the other units when the gear teeth of the forwarding unit are in correct mesh with those of the other units, and the teeth properly mesh units , the relative disposition of the units is such that when the drive unit is rotated in a direction to drive the driven unit , a resultant force of the driving forces applied to the teeth of the forwarding unit acts along a path between the centers of rotation of the other units so as to hold the teeth of the forwarding unit constantly in mesh with the correct teeth of the other units .
According to yet a further aspect of the invention, a gear train assembly comprising units of driving driven sprocket and idler wheels and first and second gears arranged either side of a line connecting the centers of rotation driving and driven units , each relay unit being movable radially with respect to at least one of the driving and driven units , each unit comprising a sprocket element and at least one coaxial cylindrical spacer the or each spacer of each idler UNI -T lying in engagement with the spacersof driving and driven units when the gear teeth of the forwarding unit are in proper mesh with the driving and driven units , and the teeth of the first mesh unit or secondidler correct teeth driving and driven units , the relative arrangement of the units is such that when the drive unit is rotated , respectively , in one direction or in the opposite direction driving the driven unit , a resultant force of the drive forces applied to the gear teeth of the first or second forwarding unit , as the case may be, acts along a path between the centers of the'rotational driven and 3. driving units in order to keep the teeth of the forwarding unit constantly correct mesh with the teeth of the other units, means being provided to prevent or restrict the movement of the teeth of each unit mesh forwarding correct the drive unit when the resultant force is not applied along said path .
In an assembly according to the invention, at least one unit may comprise two spacerslocated one on each side of the gear wheel elements , Alternatively or in addition , at least one unit, the gear wheel element can comprise two coaxially separate gear which is disposed between at least one spacer .
It is preferable that in each unit, the or each spacer has a diameter substantially equal to the pitch circle diameter of the unit.
DMWINGS brief description of embodiments of the invention will now ' be described by way of example with reference to the accompanying drawings in which:
Figure 1 is a front elevational view of a drive arrangement for a rolling mill , the drive arrangement which includes two sets of gear train according to the invention;
Figure 1A is a cross sectional view along line IA -IA in Figure 1 which shows schematically the gear train assemblies ;
FIGURE 2 is on a larger scale than Figure 1 and is a cross sectional view along the line IIII in Figure 1 , one of the assemblies illustrated schematically ;
Figure 3 is a view similar to Figure 2 of the gear train assembly which indicates the manner in which the assembly operates in practice;
Figure 4 is a cross sectional view of the line IVIV of the gear assembly of Figure 3 ;
FIGURES S , 6 and 7 are views similar to Figure 2 of the modification of the first embodiment;
Figures 8 and 9 are views similar to Figure 2 of a second embodiment showing different relative positions of drives from a reversible gear train ;
Figure 10 is a view similar to Figure 2 of a third embodiment showing different relative positions of units of a gear train assembly reversible ;
Figure 11 is an axial end view schematic of a set of gear train forming a fourth embodiment ;
Figure 12 is a view similar to Figure 11 of a fifth embodiment ;
Figures 13 and 14 are cross sectional views respectively along lines XIVXIV XIIIXIII and in Figure 12 ;
Figure 15 is an axial end view schematic of a set of gear train composed of a sixth embodiment ;
Figure 16 is a cross sectional view along the line XVIXVI in Figure 14 .
Description of the Preferred Embodiments In the following embodiments and modifications thereof , mutually identical parts bear like reference numerals .
\ In a first embodiment, shown in Figures 1 to 4 in a rolling mill comprising two drive shafts the rollers 1 operable connected to two rolling rolls (not shown) of conventional design to provide a nip to reduce the thickness of the metal strip fed therethrough . Is desirable to be able to automatically adjust the positions of the centers of the work rolls during operation of the mill to keep the rolled strip thickness between specific limits . To enable this setting a drive arrangement 2 is used as will now be described .
The " layout unit 2 comprises two sets of gear train 3 according to the invention. Each set 3 as shown in Figures 2 , 3 and 4 comprises a drive gear wheel drive and four wheel drive driven gear 5 . Unit 4 fixed gear coaxially fixed a drive shaft 6 extending from a main drive box 7, the main unit box to ensure that the two axes are driven in opposite directions with speeds equal angular . unit 5 of each set is coaxially fixed to a drive shaft 1. As shown particularly in Figure 4 , the driving unit 4 comprises a gear wheel which is a single gear wheel 8 formed integrally 9 with coaxial cylindrical spacers located on either side of the sprocket. driven unit 5 is similarly formed with a gear wheel 10 having integral spacers 11 (Figs. 1 and 2). a tensioning unit 12 comprises a wheel 13 with integral gear 14 coaxial spacers located on either side.
Spacers each having a diameter equal to the pitch circle diameter of the respective gear wheel and the teeth of the gear wheel 13 are in proper engagement with the teeth of the sprockets 8 - and 10 when the peripheral surfaces of spacers 14 lie in engagement with the peripheralsurfaces separators 9 and 11.
Three units of each set are arranged relatively so that when the gears are in proper mesh two lines extending one between the centers of rotation of the units 4 and 12 and one between the centers of rotation of units 5 and 12 produce between them an angle which is at least twice the pressure angle of the gear wheels . Preventing or restricting movement means , ie elastic means in the form of two tension springs 15 are used one on each side of each unit to maintain forwarding idler wheel correct continuous meshing engagement with the other gear wheels . Every spring extends from a'sleeve 16 can swivel unit short forwarding to a fixed support 17. For reasons to be explained , however , the spring is unnecessary to retain the idler wheel in this position during rotation of the gear wheel , while the forwarding unit is mounted on a shaft fixed relative to the other units and movable radially of the other gears .
In use of the mill , the drive shafts 6 are driven by the box unit 7 for rotating the driving units 4 . 3 in each set , the forwarding unit is operated to drive the driven unit under meshing engagement of the gears 8 and 13 and the gear wheels 13 and 10 . Each unit 4 is rotated in one direction , so that each portion of the unit moves into the space between the units 4 and 5 , as it moves away from the forwarding unit . For the upper assembly 3 the rotational arrows in Figures 2 and 3 indicate the directional movement of the units. During the rotation of each unit 4 in this direction, a force in the direction of arrow A ( Figure 3) is applied to the teeth of the sprocket teeth 13 of the gear wheel 8 . Also, as the gear wheel 13 drives the gear wheel 10, a force is applied to the teeth of the sprocket 13 by the gear wheel 10 in the direction of arrow B. Due to the relative arrangement of the units mentioned above, the resultant force C of these two forces acting on the idler unit 12 along a path between the centers of rotation of the units 4 and 5, as shown in figure 3, in order to maintain forwarding unit with spacers 14 in continuous engagement with the spacers 9 and 11 through which the teeth of gear wheel 13 are held in constant mesh with the teeth and correct the other wheels gear during rotation of the units in the directions indicated .
With this mounting arrangement , provided that the relative arrangement of the units, ie its angular relationship with respect to the pressure angle is maintained above a explained, each of the units " 5 can move into and out of its drive gear during four wheel rotation as this movement only results in a consequent and corresponding forwarding unit , while their teeth are maintained in proper mesh with the other units . Itwill be appreciated that this space movement units 5 permits the roll nip is adjusted while working metal strip is reduced in thickness to maintain the reduced thickness between the limits specified if required in each set to replace one of the units 4, 5 and unit 12 with a different pitch circle diameter of gear wheel to alter the speeds driven work rolls is a simple matter to remove the forwarding unit 12 to allow this replacement. Moreover, when a unit is added replacement , no need for manual adjustment in the position of forward drive to ensure that the gear wheel 13 meshes properly with the other gear wheels , gear wheel that correct meshing is always guaranteed , then no rotation the drive unit in the direction indicated by the virtue of the resultant force acting on C idler unit .
A further advantage obtained with each gear train assemblydescribed above is that idler wheel is always in mesh tothe correct gear wheels other despite shaft deflections or wear on the shaft bearings because any radial movement of the rotational axes of the other units in use is accommodated by corresponding movement of the automatic forwarding unit . Furthermore, as correct gear meshing always warranted , then no gear wear may occur due to incorrect meshing . Moreover, do not use a fixed mounting shaft and bearing for idler unit .
In the embodiment described above , with the use of springs 15, each gear train assembly can be used successfully in any position of the gear wheel drives with horizontal rotational axes . For example, if the units 4 and 5 are spaced horizontally positioned , instead of vertically spaced , with the unit 12 beneath the units 4 and 5, then the unit 12 is held in place by the springs when the assembly not in use .
However, in a modification of the above embodiment in which each gear train assembly of the units 4 and 5 are horizontally separated , the gear 13 is in mesh with the other gear wheels to the unit 12 located at above the other units. In this case, the springs 15 and dispenses the unit 12 is carried out automatically with the wheel 13 in mesh with the other gear wheels when the assembly is not in use , under the weight of the unit 12.
In a modification of the first embodiment as shown in figure 5, the forwarding unit , the springs 15 and the support 17 are replaced by an annular forwarding unit 18 and a movement restriction means in the form of an element cap or plug 19. Unit 18 is provided with a gear wheel 20 and spacer 21 similar to the unit 12 of the first embodiment. The stop pin is fixed at one end to a box housing the main unit 7 and extends radially and axially into the ring as shown in Figure 5.
When the gear wheel 20 is in correct engagement with the gear wheels 8 and 10, the pin is slightly separated from the inner surface 18a of the unit 18. However, when the resultant force F is not applied to the unit 18 such as occurs when the gears are not being driven or when braking gear when a resultant force in the reverse direction can be imposed on the unit 18 any movement of the grid unit 18 with the other units right is limited by engagement of the pin on the inner surface of the unit. PEG is positioned so as to stop the movement of the mesh unit 18 right before the teeth of the gear wheel 20 are completely decoupled from the gear wheel 8 . Therefore, when the resultant force is applied again to the unit 18 during the next application of the driving car operated units , this force urges the unit 18 in its correct position of the teeth mesh with the other units .
In another modification of the first embodiment shown in Figure 6 , the springs 15 and the support 17 are replaced by a restricting means in the form of a stop element . This stop element is a shoe 22 is held in fixed position in the box casing the'main unit 7 and is slightly separated from the forwarding unit 24 when the drive teeth are engaged properly with the other unit. Difiers unit 24 of the unit 12 in which no short shaft with a sleeve 16 mounted thereon . An area of ​​23 0f opposes shoe unit 24 is concave to fit the unit should leave this engages correctly with the other units in the circumstances described in the last shoe previous paragraph'The insuflicient prevents movement of the unit 24 to allow for complete withdrawal of the gear teeth of the gear wheel 8 so that the unit 24 is returned to the right of teeth mesh when the resultant force C is applied next .
In yet another modification of the first embodiment shown in Figure 7, each gear train assembly , a drive unit 25 is operable connected to a guide unit 26 by the forwarding unit 24. Units 25 and 26 are cylindrical spacers 27 and 28 to engage the standoffs 14 of the unit 24 when the gear wheels of the units are in proper mesh .
In this construct, a movement of the tightening unit preventing or restricting means comprises an endless member in the shape of a tape 29 which extends into frictional contact around an engagement surface of each drive belt 25 and 26, this surface is the peripheral surface of a cylindrical coaxial extension member 30 and 31 respectively of the units 25 and 26.
When no force is applied resulting C , frictional engagement with the belt surfaces of the extensions 30 and 31 prevents slipping rotation of the units 25 and 26 relative to each other. Accordingly, the forwarding unit is performed with proper meshing teeth with the other units by virtue of the fact that the teeth of the gear wheels 32 and 33 of the units 25 and 26 lock wheel gear 13 in position and prevent disengagement of the teeth.
In the following embodiments four fifty-eight included , it is understood that the driving , driven and tensioning units are relatively disposed in the manner specified in the first embodiment .
In a second embodiment, a rolling mill is constructed in the manner described in the first embodiment with a drive arrangement to allow automatic adjustment of the roll gap between work centers. In this embodiment , however , requires that the work rolls are reversible in their direction of rotation to allow the metal strip after being reduced in thickness in a first pass through the mill to be further reduced in the thickness in a second pass in the reverse direction . To enable this, each gear train assembly 34 ( one of which is shown in Figures 8 and 9) is different from the construction of the joint 3 of the first embodiment.
Each gear train assembly 34 comprises , as in the first embodiment, a drive unit 4 and the driven unit 5, each with their respective gear wheels 8 and 10 and spacers 9 and 11 as described in the first embodiment. However, each assembly 34 also comprises two tensioning units 12 arranged one on each side of a line connecting the centers of rotation of the driving and driven units .
Means are provided in each assembly to prevent or restrict the movement of each unit forward to move teeth properly mesh with the drive unit . These means comprise a toggle lever 35 which is pivotally mounted at the junction of its arms 36 and 37 about the axis 6. The lever is connected to the friction drive unit for sufficient frictional engagement with the lever shaft to tend to urge the lever in the same direction of shaft rotation. The relative positions of the tensioning units 12 is such that when one unit is in correct mesh with both the driving and driven units , the other forwarding unit is completely out of engagement with the driven unit (see Figures 8 and 9). This prevents tooth wear between the guide unit and idler unit not put in a proper position of the mesh at any time.
In use of the mill , when the guide unit 4 is driven in the direction of clockwise rotation as shown in Figure 8 , the forwarding unit mounted on the arm 37 is in the correct gear teeth with driving and driven units to transfer the unit to the driven unit. When the drive unit is driven in the clockwise direction (Figure 9) to reverse the direction of rotation of the rolling rolls , the resultant force C in the teeth of the forwarding unit 37 on the arm is reversed thereby pushing this mesh forwarding unit to the driven unit of the toggle rotation around axis 6. Furthermovement the bell crank lever in the same direction takes place due to their frictional engagement with the shaft to move the tensioner arm unit 36 in correct mesh with the driving and driven units . The forwarding unit is then held in this position for continued actuation in the same direction by the resultant force F along the path shown in Figure 9 .
The gear train assembly of the second embodiment has the advantages detailed above for the structure described in the first embodiment , but in addition , it also allows the reversal of the driving car operated units . In a third embodiment, a set of gear train 38 (Figure 10) incorporates a simple roller unit 12 while allowing the gap between the driving and driven units 4 to be varied and also while allowing reversal drive unit 4 reverse the direction of rotation of the unit 5 .
In this embodiment , the means for preventing or restricting the movement of the forwarding unit to move their teeth properly mesh with the drive unit comprises an arm 39 which is pivotally mounted about an axis which coincides with the center rotation of the drive unit on the drive shaft 6 . The arm is connected by friction to the drive unit by its frictional engagement with the shaft 6 so that the arm is urged to move pivotally in the same direction as the direction of shaft rotation. In use, while the driving unit 4 is rotated in the clockwise direction shown by the arrow indicated in Figure 10 complete, the forwarding unit is in correct mesh ( full outline position shown) the units 4 and 5. If the drive unit is then driven in the reverse direction , ie in the direction of the dashed arrow in Figure 10 , the arm 39 , by virtue of their frictional contact with the shaft 6, is pivotally moved around the drive unit in the counterclockwise direction to move the forwarding unit outside its correct position shown in full mesh side of the driving and driven units to a correct position mesh with these two units in the other side of the units, as shown by the dotted line . If the drive unit is activated and then again in the direction of clockwise , the arm 39 is moved by the friction also in the direction of clockwise to return the unit to its proper position forwarding mesh shown in full outline .
In a fourth embodiment shown in Figure 11 , a set of drive gear train 40 to drive a reversible mechanism comprises a drive unit 41 fixed to a drive shaft 42 and being similar in construction to the unit 4 first embodiment in that comprises a gear wheel 43 flanked on both sides by means of spacers 44 integral coaxial . A driven unit 45 secured to a driven shaft 46 and has a gear wheel 47 coaxial with integral spacers 48 is operable connected to the unit 41 by tensioning units 49 and 50 disposed one on each side of a line passing through the axes of rotation of the units 41 and 45 . Units 49 and 50 are gear wheels 51 of equal pitch circle diameter , each sprocket is flanked on both sides by means of spacers 52 integral coaxial . In each gear wheel drives in the set, the diameter of each spacer is equal to the pitch circle diameter of the sprocket. The two units 49 and 50 are urged toward each other by tension springs 53 on each side locatedone units and fixed at its ends to pins 54 coaxial units . The springs are elastic means forming unit movement preventing or restricting tensioning means . Units 49 and 50 are otherwise freely movable in a radial direction with respect to the units 41 and 45 .
In the use of the set, when the drive unit 41 is rotated in a direction clockwise to drive the driven unit 45 , the unit is provided to the unit 45 unit 49 which is supported with gear teeth . Correct meshing engagement with the gear wheels 43 and 47 by a resultant force , as described in the first embodiment. Driving forces acting on the unit 50 have a resultant force urging the distance unit 50 and to move teeth meshing with the sprockets '43 and 47 . However, the unit 50 is held with its gear teeth in mesh with the sprockets 43 and 47 by springs 53 .
When driving unit 41 in the counterclockwise direction to drive unit 45 in the same direction , the forwarding unit imparts the drive unit 45 and is held in the correct teeth meshing engagement with the sprockets 43 and 47 by a resultant force urging unit 50 to the units 41 and 45 . In this instance, the left -turn unit 41 , the unit 49 is pushed away from the units 41 and 45 but is held in position by the springs 53 .
Be appreciated that, in use, the gear train assembly of the fourth embodiment has all . the advantages to those described in the second embodiment except that the distances between the centers of driving and driven units can not be varied while the engine is carried out as opposed to idle gears mesh lock positional relationship of the centers of the driving and driven v units .
In a fifth embodiment in which the size of the gear wheels required to provide a desired gear ratio for driving a mechanism can not be accommodated in one plane due to the distance between driving and insufiicient shaft centers driven , the following construction is used as shown in figures 12, 13 and 14.
In the fifth embodiment, a set of gear train comprises a drive unit 55 comprises a gear wheel which consists of two gear wheels 56 ( Figures 13 and 14 ) which are coaxially fixed to a drive shaft 57 and are separated by a sleeve 58 . The sprockets are of equal diameter and each pitch circle wheel is provided with a spacer 59 which is formed coaxially with the wheel on its side remote from the other wheel , the diameter of the spacers , equal to the pitch circle diameter of the wheels toothed.
A guiding unit 60 , as shown particularly in Figure 14 , comprises a driven gear wheel 61 comprises a fixed to a driven shaft 62, the sprocket 61 is located in part between the sprockets 56 . The unit is provided with two spacers 63 that are secured coaxially to the shaft 62 and are separated from the gear wheel 61 by sleeves 64 so that each gear 56 and its spacer 59 is located between a spacer part 63 and the sprocket 61 . The spacers 63 have a diameter equal to the pitch circle diameter of the sprocket 61 .
A forwarding unit 65, which is freely movable radially of the other units has a gear 66 (see in particular Figure 13), which has an axial length sufiicient to close the gap between the mesh and with the sprockets 56 . The gear 66 also engages with the sprocket 61 . Unit 65 is also provided with two spacers 67 which are formed coaxially with the sprocket 66 and the flank of the gear wheel . These separators have a diameter equal to the pitch circle diameter of the sprocket 66 and are of sufficient axial length to engage the peripheral surfaces of the spacers 59 and 63 . Each of the units is symmetrical about a mid-circumferential plane of the unit so that there is no out of balance forces are imparted to the forwarding unit to vacate the unit out of its correct position during use.
In use of the gear train assembly during rotation of the driving and driven units in a direction clockwise in Figure 12 the forwarding unit is pushed toward the other units by a resultant force , as described in the first embodiment , so that spacers 67 are held in peripheral engagement with the spacers 59 and 63 so that the gear 66 is maintained in proper meshing engagement with the sprockets 56 and 61 .
In a modification of the fifth embodiment , the gear wheels 56 are provided with a single spacer (not shown ) instead of spacers 59 . This unique spacer lies between the gear wheels 56 to space apart and therefore replaces the sleeve 58 . The drive gear wheel 55 modified course requires modification corresponding to each of the other units 60 and 65 to ensure proper engagement of the gears and the participation of the spacers.
In a sixth embodiment , as shown in Figures 1H and 16, a gear train assembly 68 suited for a crane unit comprises a driven unit 69 in the form of an annulus with an element of a single sprocket wheel 70 having internal gear teeth . Integrally formed spacers 71 are provided on each side of the sprocket. A drive unit 72 is located axially radially'and ' ; - but eccentrically in the driven unit , and operable "connected" to the driven unit 73 an idler sprocket units 72 and 73 are respectively provided . wheels'74 gear and 75 and spacers 76 and 77 disposed on each side coaxiallyone gear wheels . In each unit the diameter of the spacers corresponds to the pitch diameter gear wheel Ofthe . The drive unit is drivable by a drive shaft 78 (FIGURE 16). The units are relatively arranged so that when the gears are in proper mesh produces an angle between a line connecting the centers of rotation of the forwarding unit and drive unit 72 and another extension line connecting the centers rotation of the forwarding unit and driven unit 69 is at least twice the pressure angle . me
In use of the assembly, the drive wheel is rotated in the direction clockwise as shown in Figure 15 to rotate counterclockwise driven unit . Due to the relative arrangement of the units, a resultant force F of the driving forces acting on the forwarding unit 73 in the direction indicated in Figure 15 has the forwarding unit in the correct mesh with the other units , while the unit is being imparted to the driven unit in the direction indicated .
The gear train assembly of the sixth embodiment which is not reversible in use, but otherwise has the advantages of the assemblies described in the above embodiments . In this embodiment , a particular advantage is that the drive unit is mounted eccentrically and can move radially with respect to the driven unit as long as the force F acts on the still forwarding unit to keep it in position. The need is , therefore , avoided by the precise location of the drive unit with respect to the particular engine unit , as required in conventional drive assemblies incorporating a gear concentric internally toothed ring gear .
In a modification of the sixth embodiment (not shown) is also used a second forwarding unit , the two tensioning units are mounted on the arms of a bell crank lever pivoted on the shaft 78 in a manner similar to the mounting axis 6 in the second embodiment. The assembly is then reversible operation.
In a further modification of the sixth embodiment (not shown) , the driven unit 69 is replaced by a unit which is an annular gear for driving the unit 72 which now becomes the driven gear . Diifers annular driving gear unit 72 only provided with external teeth , as well as internal teeth , the external teeth is operable connected to a worm wheel drive.
Gear train assemblies according to the invention and as described in the embodiments may be used in other mechanical devices or machines , while obtaining the advantages mentioned above. For example, the gear train sets in accordance with the invention can be used in machine tool lathe or gear or gear boxes which provide many gear ratios so that the drive shafts are particularly long , in which case the deviation of the axes is usually an important factor causing gear wear and noise due correct meshing gears . For the reasons explained in the first embodiment using the gear train assemblies according to the invention, gear wheel which meshes properly achieved regardless of shaft deflections and wear of bearings.
One important use of the gear train assemblies according to the invention is for driving the spindles of the drill heads or nut runners multiple machine , each spindle is driven by an adjacent mandrel by a set of train gear . Such a system allows changing the wheelbase of the mandrels and for changing gear ratios without the use of universal joint shafts . Additional sets of gear train may , for example, be used in positive units in small mechanisms in which it is particularly desirable that there is no need for a fixed shaft and bearing assembly for the idler gear due to space limitations . The gear wheel drives the mechanism of this type can be made, for example, rubber or plastic instead of metal.
Claim: v

'L- A gear train assembly comprising a gear wheel drive a driven sprocket and an idler wheel to drivablyconnecting driving and driven sprockets wherein the improvement comprises at least one coaxial cylindrical spacer each gear wheel , the idler gear wheel and spacer are movableradially associated with respect to at least one of the other gear wheels and their respective spacer, the spacer lying idle gear wheel in engagement with the spacers of the other gear wheels when the idler gear wheel is in proper engagement with the other gear wheels , gear wheels and being arranged relative to each other during driving of the gear wheels for applying a driving force resulting loca gear wheel along a path between the centers of rotation of the other gear wheels to maintain constant gear wheel nuts in proper mesh with the other gear wheels .
Two . An assembly according to claim 1 wherein the driving and driven gear'wheels are movable relative to each other to adjust the distances between their centers of rotation.
Three . An assembly according to claim 2 including means operatively connected to at least one gear wheel , to prevent or restrict the movement of the idler gear wheel properly mesh with the gear drive when it is applied saidresultant force .
April . An assembly according to claim 3 wherein the movement preventing or restricting means comprises a resilient means operatively connected to the idler wheel to hold it in a position where it is in continuous meshing engagement with wheel correct drive gear .
May . An assembly according to claim 3 wherein the idler gear wheel is a ring gear having teeth on an outer surface of the outer ring, and movement preventing or restricting means comprises a stop element which extends through the ring in a position to engage the idler wheel to sufiicient prevent movement of the idler wheel away from the drive gear wheel completely to disengage the two gear wheels .
June . An assembly according to claim 3 wherein the movement preventing or restricting means comprises a stop element is opposed to the idler wheel in a position to engage the intermediate gear wheel for preventing movement of sufiicient idler wheel away from the drive gear wheel completely to disengage the two gears .
July . An assembly according to claim 3 wherein the movement preventing or restricting means comprises an endless member and each of the driving and driven sprockets is provided with a coaxial cylindrical extension having an outer peripheral surface around the endless member which extends and is in frictional engagement to prevent relative rotational sliding of the driving and driven sprockets .
August . An assembly according to claim 3 wherein the movement preventing or restricting means comprises an arm pivotally mounted about an axis coincident with the axis of rotation of the drive gear wheel , the idler wheel is rotatably mounted on the arm at a fixed distance from the pivot axis , said arm being connected to the friction drive gear wheel and pivotally movable by the drive gear wheel during reversal in rotation to move idler gear wheel from a position on one side of the driving and driven sprockets , around the drive wheel and a position on the opposite side of said gear wheels and allow the assembly to conduct alternately in both directions.
9. An assembly according to claim 1 , which includes first and second gear wheels arranged on either side of a line connecting the centers of rotation of the driving and driven sprockets , the gear wheels being arranged relative to each other during rotation the drive gear wheel in one direction and alternately in the opposite direction to apply a driving force resulting , respectively ,
alternatively the first and second gear wheels along a path between the centers of rotation of the driving and driven sprockets to maintain the first and second idler gears constantly meshed with the driving and right driven sprockets , means associated with toothed wheels being provided to prevent or restrict movement of each idler gear correct mesh with the gear drive when said resultant force is not applied along said path .
10 . An assembly according to claim 9 wherein the preventing or restricting movement means comprise a crank pivotally mounted about an axis coincident with the axis of rotation of the gear wheel drive and idler sprockets are rotatably mounted one on each arm of the lever , the distance between the two idler wheels to ensure that when one of the idler gear wheel is in correct mesh with driving and driven sprockets , the other idler wheel is completely out of engagement with the driven gear and the friction lever is connected to the drive wheel pivotally moving the shift lever on the rotation of the drive gear wheel to move a wheel idler gear mesh with driven unit and to move the other idler gear wheel in mesh with the gear driven .
11. An assembly according to claim 9 wherein the movement preventing or restricting means is an elastic means extending from one wheel to the other intermediate gear .
12. An assembly according to claim 1 wherein the gear wheels have a pressure angle , each gear has an outer peripheral surface for -med with gear teeth , and
Gear wheels are relatively arranged to produce a " angle between a line connecting the centers of rotation of the intermediate gear wheel and the gear wheel drive and a line connecting the centers of rotation of the intermediate gear wheel and the driven gear wheel , said angle being produced at least twice the pressure angle .
13. An assembly according to claim 1 wherein the gear wheels have a pressure angle , one of the driving and driven sprockets is a ring having an inner peripheral surface formed with gear teeth , and the gears are relatively arranged to produce a line connecting centers of rotation angle betweenone wheel and driving idlergear not override or driven wheel , and an extension of another line connecting the centers of rotation of the intermediate gear wheel and the ring , said angle produced at least twice the pressure angle .
14. An assembly according to claim 1 wherein each spacer has a diameter equal to the pitch circle diameter of the respective gear wheel .