Marine reversing gearing

A marine reversing gearing having a drive shaft, a forward clutch, a forward pinion coaxially arranged with respect to the drive shaft and capable of being coupled therewith by means of the forward clutch for forward travel. Two intermediate gears continuously mesh with the forward pinion, there also being provided two intermediate pinions which are rigidly connected with a respective one of the intermediate gears. A large gear continuously meshes with both intermediate pinions. There are also provided a reverse clutch and a rearward pinion which is coaxially arranged with respect to the drive shaft and can be coupled therewith by the reverse clutch for rearward travel, and two reversing pinions are driven by the rearward pinion. The intermediate gears meshing with the forward pinion exclusively transmit power as forward gears during the forward travel. Both of the reversing pinions mesh with the rearward pinion and with a respective rearward gear, and each of both intermediate pinions also are fixedly connected with one of the rearward gears.

CROSS-REFERENCE TO RELATED APPLICATIONS 
Application Ser. No. 919,045, filed June 26, 1978, contains subject matter 
related to this application and was filed by the same applicant and 
assignee herein. 
BACKGROUND OF THE INVENTION 
The present invention relates to a new and improved construction of marine 
reversing gearing or power transmission system for vessels or the like. 
The marine reversing gearing of the present invention is of the type 
comprising a drive shaft, a forward clutch, a forward pinion arranged 
essentially coaxially with regard to the drive shaft and capable of being 
coupled therewith, during forward travel, by means of the forward clutch. 
There are also provided two intermediate gears which continuously mesh 
with the forward pinion, two intermediate pinions which are fixedly or 
rigidly connected with a respective one of the intermediate gears, a large 
gear which continuously meshes with both intermediate pinions, a reverse 
clutch, a rearward pinion which is coaxially arranged with regard to the 
drive shaft and can be coupled therewith, during rearward travel, by means 
of the reverse clutch, and two reversing pinions which are driven by the 
rearward pinion. 
A prior art marine reversing gearing of this type, for instance as 
disclosed in U.S. Pat. No. 2,741,351, particularly FIGS. 3, 4 and 5 
thereof, has the rearward pinion meshing with one of the reversing pinions 
and such being coupled by means of an additional clutch with the second 
reversing pinion. The additional clutch is always disengaged whenever the 
forward clutch is engaged, and is furthermore always engaged when the 
reverse clutch is engaged. The second reversing pinion meshes continuously 
with the same intermediate gears with which there also continuously mesh 
the forward pinion. These intermediate gears are thus provided for power 
transmission during rearward travel as well as during forward travel. 
While, however, during forward travel there is accomplished directly at 
the forward pinion a branching-off of the power, so that its group of 
gears which mesh with both of the intermediate gears only are loaded with 
a respective one-half of the drive power, during reverse travel there does 
not yet occur any branching-off of the power at the rearward pinion, since 
such must transmit the entire power to the first reversing pinion. The 
high loading of the rearward pinion and the first reversing pinion, 
occurring during rearward travel, renders it impossible to allow a vessel 
equipped with the heretofore known type of marine reversing gearing to 
travel rearwardly at full load or power output over a longer period of 
time. In the meantime vessels have been designed for fulfilling particular 
purposes, especially ice breakers, which throughout their period of use 
can travel approximately equally as long in reverse direction as in 
forward direction and during the rearward travel require the same drive 
power as during forward travel. 
SUMMARY OF THE INVENTION 
Therefore, with the foregoing in mind it is a primary object of the present 
invention to provide a new and improved construction of marine reversing 
gearing which is not associated with the aforementioned drawbacks and 
limitations of the prior art proposals. 
Another and more specific object of the present invention is directed to 
the provision of a new and improved construction of marine reversing 
gearing of the previously mentioned type which with high power output can 
be equally suitably employed for rearward travel as well as also forward 
travel, and still requires extremely little space. 
Yet a further object of the present invention is to provide a new and 
improved construction of marine reversing gearing or transmission which is 
relatively simple in design, quite economical to manufacture, extremely 
reliable in operation, not readily subject to breakdown or malfunction and 
requires a minimum of maintenance and servicing. 
Now in order to implement these and still further objects of the invention, 
which will become more readily apparent as the description proceeds, the 
marine reversing gearing or transmission of the present development is 
manifested by the features that the intermediate gears, meshing with the 
forward pinion, exclusively transmit as forward gears the power during the 
forward travel. Further, both of the reversing pinions mesh both with the 
rearward pinion and with a respective reversing or rearward gear, and each 
of both intermediate pinions also are fixedly or rigidly connected with 
one of the reversing gears. 
In this way there is achieved the beneficial result, both during rearward 
travel and forward travel, there occurs branching-off of the power at the 
pinion coupled with the drive shaft. The rearward pinion thus can have 
essentially the same dimensions as the forward pinion, and can be equally 
greatly loaded. The reversing gears which are rigidly connected with the 
intermediate pinions, while in comparison with the heretofore known 
species of transmission, constitute additional elements or components, yet 
however do not require any appreciable additional space, since each of 
them is arranged upon a common shaft with one of the related intermediate 
pinions and forward gears. 
Continuing, it is to be noted that from German Pat. No. 1,116,106 there is 
also indeed known a marine reversing gearing which is equally loadable 
during rearward travel as during forward travel. Yet, in this case there 
is taught a transmission having only a single drive pinion which is 
continuously connected with the drive shaft. This drive pinion meshes with 
two intermediate gears which are rigidly connected with a respective first 
reversing pinion. Both of the first reversing pinions can be coupled, by 
means of a respective forward clutch, with a respective forward pinion 
which meshes with a large gear. Further, a second reversing pinion meshes 
with each of both first reversing pinions. The second reversing pinions 
can be connected by means of a respective reverse clutch with a respective 
rearward pinion and the rearward pinions likewise mesh with the large 
gear. With this known transmission there is realized the advantage that 
there can be accomplished power branch-off during rearward travel and also 
during forward travel already directly at the pinion seated upon the drive 
shaft. On the other hand there prevails the disadvantage that there are 
required two forward clutches and two reverse clutches and the number of 
the totality of required pinions likewise is greater than with the 
inventive transmission or marine reversing gearing. Therefore, also the 
space requirements of this state-of-the-art transmission is 
correspondingly great. 
According to a preferred construction of the inventive marine reversing 
gearing both of the rearward gears have operatively associated therewith a 
respective brake. 
For engaging and disengaging the forward and reverse clutches the drive 
shaft is preferably connected by means of a clutch or equivalent structure 
and a self-locking gearing with a slowly rotating auxiliary drive.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Describing now the drawing, a drive shaft 12 is rotatably mounted in a row 
of aligned bearings 10, this drive shaft 12 being continuously coupled 
with a drive unit or machine 14, for instance a gas turbine. The drive 
shaft 12 extends through a first hollow shaft 16 and a second hollow shaft 
18. Connected with the end of the drive shaft 12 which is remote from the 
drive machine or unit 14 is an auxiliary drive 26, for instance an 
electric motor, the connection being accomplished by means of a back stop 
or return movement blocking device 20, a pair of spur gears 22 and a 
self-locking worm gearing 24. 
The first hollow shaft 16 is connected, during forward travel, with the 
drive shaft 12 by an engaged clutch which thus in the description to 
follow will be referred to by way of convenience as the forward or ahead 
clutch 28. Attached to this hollow shaft 16 is a pinion 30 of a first 
gearing stage or gear train, hereinafter conveniently referred to as the 
forward pinion 30, which furthermore continuously meshes with two gears of 
the first gearing stage or gear train and designated hereinafter as the 
forward gears 32. These forward gears 32 are mounted essentially in 
parallelism with one another in a respective pair of bearings 34 or 
equivalent structure and are fixedly connected by means of a respective 
torsion shaft or bar 36 with a respective pinion 38 of a second gearing 
stage or gear train, these pinions 38 being referred to conveniently 
hereinafter as intermediate pinions 38. Both of the intermediate pinions 
38 are mounted in a respective pair of bearings 40 and can be braked by a 
respective double disk brake 42 or equivalent structure and both mesh with 
a common large gear 44. This common large gear 44 is secured to a drive 
shaft 48 mounted in bearings 46 and is continuously connected by means of 
such drive shaft 48 with the propeller 50 of the ship or vessel. 
The large gear 44 has been shown laterally offset in order to simplify and 
improve the clarity of the illustration, something which, however, should 
not be misleading in terms of the fact that it continuously meshes with 
both intermediate pinions 38. 
The second hollow shaft 18 is connected with the drive shaft 12 by means of 
a clutch which can be used for the reverse or rearward rotation of the 
ship's propeller and therefore has been conveniently designated 
hereinafter as the reverse or rearward clutch 52. Secured to the second 
hollow shaft 18 is a rearward or reversing pinion 54 which meshes with two 
reversing pinions 58 stationarily mounted in bearings 56. Each of both 
reversing pinions 58, in turn, mesh with a rearward or reversing gear 60. 
The rearward gears 60 and the rearward pinion 54 have been shown partially 
covered by both of the reversing pinions 58. The rearward or reversing 
gears 60 are mounted essentially parallel to one another in stationary 
bearings 62 and are rigidly connected by means of a respective torsion 
shaft or bar 64 with a respective one of both intermediate pinions 38. 
The mode of operation of the illustrated marine reversing gearing or 
transmission, constructed according to the invention will be described 
hereinafter based upon the example of reversal of the vessel from full 
travel ahead to full rearward or astern travel: 
1. The drive unit 14 is placed into its idle mode, the auxiliary drive 26 
is started in its forward rotational direction and the back lock or 
reverse or return movement blocking device 20 is prepared for automatic 
locking action. 
2. The disk brakes 42 are engaged as soon as: 
(a) the propeller rotational speed has dropped to a predetermined value, or 
(b) there has elapsed a predetermined time. 
3. When the rotational speed of the drive shaft 12 has dropped below the 
low rotational speed of the reverse movement blocking device 20 such 
engages and automatically locks. 
4. As soon as the reverse movement blocking device 20 is locked, then the 
auxiliary drive 26 is reversed from its forward mode to its backwards or 
reverse mode. At the same time the synchronization mechanism of the 
forward clutch 28 is placed out of operation, that of the reverse clutch 
52 into operation. 
5. During the reverse rotation of the drive shaft 12 through about 
30.degree. the forward clutch 28 disengages. 
6. As soon as the forward clutch 28 has disengaged then the auxiliary drive 
26 is once again reversed and rotates the drive shaft 12 forwards. As a 
result, the reverse clutch 52 engages. 
7. As soon as the reverse clutch 52 has completely engaged, then the 
auxiliary drive 26 overcomes the idling moment of the drive unit 14 and 
thereby relieves the locking action of the reverse movement blocking 
device 20, so that such can be easily disengaged. Thereafter, the 
auxiliary drive 26 is brought to standstill. 
8. The disk brakes 42 are released. For the case that the vessel continues 
to still travel forward, then the propeller 50 of the vessel strives to 
rotate forwardly and thus to rearwardly rotate the drive unit 14. This is 
prevented by the stopped auxiliary drive 26 in conjunction with the 
self-locking gearing 24 and the reverse movement blocking device 20. 
9. Now the rotational moment or torque of the drive unit 14 can be 
increased. As soon as it exceeds the propeller torque then the turbine 
begins to rotate forwardly, the reverse movement blocking device 20 
releases and the propeller 50 begins to rotate backwards. 
The reversal from rearwards to forwards occurs in the exact same steps, 
only the clutching functions of the forward and reverse clutches are 
interchanged. 
While there are shown and described present preferred embodiments of the 
invention, it is to be distinctly understood that the invention is not 
limited thereto, but may be otherwise variously embodied and practiced 
within the scope of the following claims. Accordingly,