Driving device for rail vehicles having friction and cog drives

A driving device for rail vehicles having both a friction drive and a cog gear drive has a common drive shaft placed in the longitudinal direction of the rail vehicle. The drive shaft is provided with driving worms which mesh with worm gears on the driving axles of the friction drive and the cog gear drive. The worms are axially spaced on the drive shaft and engage the respective drive gears of the friction and cog gear drives which are located under the drive motor so as to obtain greater traction force with the friction drive and a more positive meshing of the cog gear with the rack.

The present invention relates to the driving mechanism for rail vehicles, 
more particularly, to such a drive mechanism in which a drive motor on the 
vehicle can be drivingly connected with a friction rail drive and a cog 
gear drive. 
In addition to the large number of known cog wheel or rack railroads having 
steam locomotives, steam rail cars, electric locomotives and rail cars, as 
well as rail vehicles with internal combustion engines, those railroads 
having mixed cog wheel and friction rail sections include the largest 
portion of all cog wheel rail vehicles which have been constructed. 
There is a particularly great diversity in the constructions of rack steam 
locomotives which range from a two-axle locomotive with a coupled driving 
mechanism and one driving cog wheel to multi-axle locomotives having 
four-axle friction trucks and a separate three-axle cog gear truck. The 
present invention is primarily concerned with that type of drive wherein 
power units have coupled driving mechanisms, such as those with 
disconnectible rail friction drives and power units having separate 
driving mechanisms. With respect to the types of drives, reference is made 
to the publication "Zahnradbahnen der Welt" [Rack Railroads of the 
World]by Walter Hefti. 
It is to be noted that in the case of coupled rail friction and cog gear 
drives, the gear transmission ratios between the drive motor and the drive 
axle or the friction drive on the one hand and the drive motor and driving 
pinion for the cog wheel on the other hand are the same size. 
Coupled driving mechanisms were used, for example, with electrification of 
the Visp-Zermatt line, in the locomotives of the Furka-Oberalp line and in 
the mountain locomotives of the Bruenig lines. 
The freight locomotives on the Martigny-Chatelard line which were first 
placed into operation in 1905 used two drive motors mounted on the frame 
which drove the two driving pinions of the cog wheels through double gear 
transmissions. The axles of the driving pinions were provided with crank 
arms from which the friction drive was produced through four connecting 
rods. Since each driving pinion was driven by a separate motor, balancing 
of the gear tooth pressure was also resolved. 
The rail cars of the Bex-Villars-Bretaye line which were put into operation 
in 1940 employed a driving mechanism installed in a truck. A drive motor 
mounted on the frame along the longitudinal axis of the rail car was 
connected by a friction clutch to an intermediate gear from whose drive 
shaft a carden shaft transmitted the torque to the axle drive. A bevel 
gear, whose secondary shaft carried the two pinions for both the cog and 
friction drives, was mounted on the axle drive as a first transmission. 
These pinions meshed with the gears, one of which was connected to the 
driving pinion for the cog and the other was press fitted on the axle for 
the friction drive. 
Coupled driving mechanisms were used primarily on railroad lines having 
relatively small capacities and only short rack distances. The known 
disadvantages of coupled driving mechanisms could be compensated by a 
relatively simple construction in which the driving pinion is press fitted 
directly onto one friction axle. However, this construction can be 
employed only in the case of model railroads and not in public rail 
transportation. Presumably, this construction was not employed because the 
pitch line of the rack and the upper rail surface would have had to be at 
the same height which would then present difficulties in the cog wheel 
with the crown line when switching to friction rail stretches. 
Driving mechanisms having disconnectible friction drives were employed only 
in those railroad lines which had a relatively short friction section 
serving as an access stretch to a relatively long and continuous rack 
stretch. Thus, for example, the rail cars on the Aigle-Leysin line are 
made according to the same concept as the rail cars used on the 
Bex-Villars-Bretaye line discussed above except for the difference that 
the drive gear for the friction or adhesion drive is not pressed onto the 
drive axle, but that this axle is driven by an oil clutch located inside 
of the drive device. After descent of the rail car onto the rack, the 
driving motor for the oil pump is cut off and thus the oil under pressure, 
which produces the nonpositive connection between the ring gear and hub, 
is discharged. The friction drive is thus engaged. 
In addition to the safety requirements that a rack must be so constructed 
that the cog wheel is never completely disengaged from the rack and the 
rack must have a safety factor of at least six with respect to a 
prescribed maximum train weight, rack locomotives were equipped with 
additional safety features in addition to those safety features commonly 
found on rail friction locomotives. For example, each such locomotive had 
to be provided with several special brake devices which act both on the 
gear and friction drives. 
It is therefore the principal object of the present invention to provide a 
novel and improved driving mechanism for rail vehicles having both rail 
friction and cog wheel drives. 
It is another object of the present invention to provide such a driving 
mechanism which is simple in construction, reliable in operation over long 
periods of time and requires a minimum of maintenance while providing a 
high degree of functionality. 
It is a further object of the present invention to provide such a driving 
mechanism which is relatively low in cost and which can readily be 
incorporated in model rail vehicles. 
The objects of the present invention are achieved by providing a drive 
shaft extending in the longitudinal direction of the rail vehicle and the 
drive shaft is drivingly connected with gears of angular gear drives with 
one such angular gear drive having a gear fixed on a driving axle for the 
friction drive and another angular gear having a gear fixed on the drive 
axle of the cog wheel. The resulting structure is relatively simple with a 
minimum of structural details, is characterized by a compact construction 
which can be incorporated in relatively narrow and limited space 
conditions and provides for optimum operating features. 
According to one aspect of the present invention, there may be provided a 
drive device for a rail vehicle having both friction and cog drives 
wherein a drive shaft is drivingly connected to a drive motor and disposed 
in the longitudinal direction of the vehicle. The friction drive has a 
friction drive gear fixed on a friction drive axle and the cog drive has a 
cog drive gear fixed on a cog drive axle. The drive shaft is positioned 
above both the drive axles. A plurality of angular gear drives drivingly 
connect the drive shaft with the friction and cog drive gears 
respectively. 
While not so limited, the present invention is particularly adapted to 
locomotives having electric drive motors and operating on gages narrower 
than the usual standard gage. Further, the construction of the present 
invention is relatively simple so that the manufacturer of model rail 
vehicles can faithfully reproduce this drive mechanism at reasonable cost 
and still obtain favorable operating characteristics. 
While the prior art constructions as described previously are purely 
mechanical drive systems which have proven themselves over several decades 
and only recently are being replaced by other systems, these prior art 
systems can be manufactured only at considerable costs and are relatively 
difficult to transfer to model rail vehicles at reasonable costs.

Proceeding next to the drawings wherein like reference symbols indicate the 
same parts throughout the various views, a specific embodiment and 
modifications of the present invention will be described in detail. 
In FIGS. 1 and 2, there is indicated generally at 1 a truck of an 
electrically driven locomotive which has a driving mechanism indicated 
generally at 4 comprising a rail friction or adhesive drive indicated 
generally at 2 and a cog gear drive indicated generally at 3. The truck 1 
has a truck housing 10 comprising a lower truck housing portion 7 and an 
upper truck housing portion 8, both of which are detachable from each 
other. Drive axles 5 and 6 of the friction drive are mounted in the lower 
housing portion 7 together with drive axle 12 upon which is fixed a 
driving pinion of cog gear 11 which is engageable with a rack positioned 
substantially between the rails upon which the locomotive operates. 
Angular gear drives 13 and 14 drivingly connect drive axles 5 and 12 with 
a common drive shaft 15 which extends in the longitudinal direction of the 
vehicle and is positioned above these drive axles. The drive shaft 15 is 
drivingly connected with a drive motor 16 which is mounted on a 
substantially vertically disposed carrier plate 17 in the upper housing 
portion 8. The drive motor 16 has a drive shaft 18 extending directly 
therefrom and a pinion gear 19 is mounted on the drive shaft 18. The 
pinion gear 19 engages an idler gear 20 which is mounted on the carrier 
plate 17 and is freely rotatable. The idler gear 22 in turn meshes with a 
driving pinion 21 fixedly mounted on the drive shaft 15. The gears 19, 20 
and 21 thus form a back gear or gear transmission 22. 
The angular gear drives 13 and 14 illustrated in the drawings are worm 
drives which are particularly suitable for the present embodiment. 
However, bevel gear or bevel gear-worm drives could also be used but such 
drives may be somewhat more expensive in construction. 
In the worm drives of the present embodiment, the drive shaft 15 which is 
laterally offset from the longitudinal center line of the rail vehicle and 
is mounted in the lower truck housing 7 is provided with two axially 
spaced driving worms 23 and 24 which mesh with bevel gears 25 and 26 which 
are respectively fixed upon driving axle 5 and drive axle 12 of the cog 
gear. The worm gear and worm construction provides for high efficiency of 
the transmission of power and a virtually noiseless operation. 
Because the rack which projects above the upper surface of the rails and 
both the friction and cog drives are driven by a common drive shaft, the 
pitch diameter of the driving pinion 11 for the cog drive is smaller than 
the pitch diameter of the drive gears 25 and 26 on the drive axles 5 and 6 
for the friction drive. Thus, in order to obtain the same speed of the 
drive wheels and driving pinion 11 along its pitch line from the angular 
worm drives 13 and 14, there must be a gear reduction which corresponds to 
the ratio of the diameters of the drive wheels 27 and 28 and pitch 
diameter of the driving pinion 11. Accordingly, the reduction in the worm 
drives for the drive wheels 27 and 28 on the drive axles 5 and 6 with 
respect to the diameters is less than the reduction for the driving pinion 
11. The drive axle 12 of the driving pinion 11 is located in the plane 
formed by the drive axles 5 and 6. The pitch diameters of the driving 
worms 23 and 24 are equal. It is necessary that the effective height of 
the teeth on the rack project above the upper edges of the rail because of 
the presence of switches installed on rack railroads. Because of the 
existence of the middle rail of the switches, the cog gear of the cog 
drive must have its crown line raised above the upper edge of the middle 
rail by a short distance so that the cog wheel can readily pass over the 
switch rails without contact. 
Since both the drive wheels of the friction drive and the cog gear of the 
cog drive should have the same peripheral speed on the rails and rack 
respectively, it is apparent that the structure according to the present 
invention enables this characteristic to be achieved. This means that the 
reduction in the worm gear for the friction drive is less than the 
reduction in the worm gear for the cog drive. It has also been found that 
for manufacturing purposes it is advantageous when the drive axle of the 
cog gear is at least substantially in the same plane which is defined by 
the drive axles of the drive wheels of the friction drive. To further 
simplify production the driving worms on the drive shaft have the same 
pitch diameter. These driving worms 23 and 24 on the drive shaft 15 are 
self-locking so that in the case of steep rack sections the running speed 
can be controlled by the motor propulsion power. At the same time, the 
rail vehicle will hold its position during a stop by making an ascent 
because of the self-locking feature without the necessity for additional 
braking. 
In order to improve efficiency, the driving worms 23 and 24 are made 
multi-threaded or double threaded. The lateral offsetting of the drive 
shaft with respect to the longitudinal center line of the rail vehicle 
results in a more compact construction. 
Adhesion of the drive wheels 27 and 28 with respect to the rails and 
engagement of the cog gear 11 in the rack is improved by positioning the 
drive motor 16 over the drive axle 5 and drive axle 12. The weight of the 
motor thus improves the friction drive and engagement between the cog gear 
and the rack. 
A coupling device may be provided on drive shaft 15 between the drive worms 
23 and 24 in order to uncouple the friction drive from the gear drive. The 
back or transmission gear system 22 is provided on the end of the drive 
shaft 15 which is opposite the end of the drive shaft intended for the 
friction and cog drive. Subsequently, a second bearing of the drive shaft 
15 could be mounted directly onto the driving pinion 21 in the case where 
the friction drive is produced only on one drive axle 5. Since in the 
present embodiment both axles 5 and 6 are driven, the drive shaft 15 is 
provided with a shaft extension 29. On the end of the shaft extension 29 
or somewhat before its bearing, there is provided a drive worm 30 which 
corresponds to the structure of the other drive worm 23 for the friction 
drive. The drive worm 30 meshes with bevel gear 31 which is fixed to the 
drive axle 6. It is apparent that the drive shaft 15 can be mounted in the 
same manner but without any drive to the drive axle 6. However, the 
present embodiment of a two-axle drivable truck is a preferred 
construction. 
In the truck or rail vehicle of the present invention as illustrated in 
FIG. 1, it is preferable that drive axle 5 function as the rear running 
axle of the truck. Accordingly, it is further preferable that the cog gear 
11 be positioned adjacent to or at least close in the vicinity of the 
running axle 5 so as to be directly under the driving motor 16 and thus 
the cog gear is further offset from the running axle 6 functioning as the 
front axle of the rail vehicle. 
In the rear wall of the lower truck housing portion 7 there is detachably 
fastened a bearing block 32 which supports a bushing 34 in which is 
journaled an end 35 of the drive shaft 15. In a similar manner, bearing 
block 33 is mounted in the opposed front wall to support a sleeve bearing 
or bushing 34 in which is journaled the other end 36 of the drive shaft 
15. In order to limit axial displacement of the drive shaft 15 stop plates 
38 and 39 are slid downwardly into vertically extending slots 37 formed in 
opposed ends of the lower truck housing portion 7. One stop plate 38 may 
function to secure the bearing block 32 in position. This mounting of the 
drive shaft facilitates a removal and installation of the entire driving 
mechanism and can also be employed for a pure friction drive without any 
cog drive. 
It is preferable that the separation line of the truck housing 10 into the 
upper and lower portions 7 and 8 occur immediately above the bearing 
blocks as shown in FIG. 1. However, it would also be possible to separate 
the housing along a line below the bearing blocks of the drive shaft 15. 
However, because of the precise engagement ratios in the angular gear 
drives 13 and 14, it is preferable that the separation line be above the 
bearing blocks as illustrated. 
The truck housing 10 hermetically encloses the driving mechanism 4 of the 
friction and cog drive and therefore offers protection from dirt and 
foreign objects and against the loss of lubricant. Such a construction is 
particularly useful for model rail vehicles wherein the upper and lower 
housing portions 7 and 8 are secured by screws 40 one of which is shown in 
FIG. 1. 
An upwardly projecting bearing plate 41 is mounted on the upper housing 
portion 8 along its longitudinal center line to provide for mounting of 
the truck pin center plate of the truck 1 on a rail vehicle. The rigidity 
and strength of the truck housing facilitates this pivotal mounting of the 
truck. 
If the rail vehicle is intended to run only on flat stretches of track, the 
gear drive can be removed from the drive mechanism or even eliminated from 
the drive mechanism. In addition, the operating speed of the vehicle can 
be modified by interchanging the gears of the gear transmission 22 for 
other gears providing a desired drive ratio. 
The cog gear drive 3 and the arrangement and relationship of the individual 
components as mounted in truck housing 10 are shown in FIG. 3. The housing 
10 and the bevel gears and the cog gear 11 may be molded from suitable 
plastics but the entire rail vehicle may also be made from metal 
materials. The gears 11 and 26 are press fitted on the drive axle 12 or 
may be secured to the axle in another known manner such as by keys. 
The friction drive 2 in truck housing 10 is shown in FIG. 4. 
It is pointed out that the disclosed embodiment can be employed to produce 
rail vehicles of this type also without a cog gear drive or may be 
constructed so as to be subsequently provided with a cog gear drive at a 
later time. If a vehicle is produced without the cog gear drive, then the 
bearing passages 42 and 43 of the drive shaft 12 may be sealed with a 
suitable sealant which is not shown in greater detail but which can be 
inserted from the exterior of the housing. At the same time, the several 
gears comprising the back gear 22 may be interchanged with other gears so 
as to obtain a higher running speed. 
Thus it can be seen that the present invention has disclosed a simple but 
reliable drive mechanism for a rail vehicle having both a friction drive 
and a cog wheel drive. The disclosed driving mechanism may be incorporated 
either on full size rail vehicles or on model rail vehicles. The 
simplicity of the structure greatly facilitates the adaptation of the 
drive system for model rail vehicles. The drive mechanism is extremely 
compact but will function reliably over long periods of time. 
It will be understood that this invention is susceptible to modification in 
order to adapt it to different usages and conditions, and accordingly, it 
is desired to comprehend such modifications within this invention as may 
fall within the scope of the appended claims.