Multiple drum winches

A multiple drum winch is driven by epicyclic differential gearing. One drum (1) rotates with the planet carrier (29, 55) and another drum (2) rotates with the annulus (35, 59) to which it is directly geared, the input being to the sun (27, 53), possibly via reduction gearing (50, 51). The epicyclic can be housed within one of the drums (1). The gear ratios are selectable to achieve a balance between the power requirements of the drums. The drums are journalled only at intermediate zones (22, 23) spanning the centroid of the expected load.

This invention relates to multiple drum winches. 
For many applications a single drum winch is inadequate, and there have 
been developed several kinds of multiple drum winches which afford greater 
power, better control, and a kinder lead for the wire. However, the 
problem is to ensure that the load is properly shared between the drums, 
which of course have to rotate at related speeds. Generally, the drum 
around which the first turn is taken is likely to be under the greater 
load, and will therefore require the greater power. 
Hitherto, the practice has often been to drive the capstan drums from a 
single motor and to use some form of splitter gear or otherwise "strap" 
the drums together for uniform rotation. However, the unequal loading on 
the drums means an asymmetrically loaded gear train. An alternative has 
been to provide separate motors for each drum, but as a result of the 
different loads there tend to be different speeds of rotation, and usually 
the drums still have to be strapped together. 
The aim of this invention is to avoid the expense and complexity of 
multiple motors and associated gears, and to drive the drums from a single 
motor through a simple gear system which fairly distributes the load. 
According to the present invention there is provided a multiple drum winch 
wherein the drive to the drums is through a differential gear train, the 
rotation of one drum being tied to that of a carrier of an intermediate 
gear and the rotation of another drum being tied to that of another, 
non-input gear. 
With this differential coupling between the drums, no gear need be 
rotationally fixed and the gear ratios can be chosen to achieve a suitable 
balance between the power requirements from the respective drums. The 
expected co-efficient of friction can be known to within quite narrow 
limits and be used in determining the gear ratios. 
In the preferred form, the drive is to the sun of an epicyclic train, the 
planet carrier is fixed to said one drum, and the annulus of the epicyclic 
is geared to the other drum. The epicyclic can be housed within said one 
drum, or within a fixed mounting for the drums, where there may also be 
reduction gearing at the input to enable a high speed motor to be used. 
Conveniently the drums are carried by bearings located internally at an 
intermediate load balancing zone, which would be approximately one third 
of the axial distance of the drum from the end at which the first turn of 
the cable is taken. Bearings at the ends of the drums would not be 
necessary.

The general arrangement is shown in FIGS. 1 and 2 where two grooved capstan 
drums 1 and 2 are mounted on a base 3 and are driven by a hydraulic motor 
4. Attached to one end of the base is an upwardly angled bracket 5 below 
which is pivoted a fairlead assembly 6. This consists of a pulley wheel 7 
rotatable between two parallel plates 8 which are fixed to part of a hinge 
9 along the sloping underside of the bracket 5. Two arms 10 extend from 
the axis of the wheel 7 to beyond its radius, where they are joined by a 
deadeye or bush 11. These arms can swing between two extreme positions, as 
indicated in FIG. 2, about the axis of the wheel 7, the passage through 
the deadeye being aligned tangentially with the circumference of the 
wheel. Thus a wire is guided truely on to the wheel from a wide compass by 
virtue of the hinge 9 and the swinging arms 10. The wire leaves the wheel 
7 and after one turn around the first drum 1 continues around both drums 
until taken off via further guide pulleys 12, 13 and 14 to a take-up drum 
15, by which time it will only be under light tension. The drive to the 
drum 15 can be coupled differentially via a hydraulic or electric motor to 
the drive for the drums 1 and 2. There will be failsafe brakes for both 
the take-up drum 4 and the capstans, operating on hydraulic failure for 
example. 
Referring now to FIG. 3, the base 3 comprises a base plate 16 and a body 17 
which provides a gear housing and mountings for both drums 1 and 2. The 
body 17 is of oblong form and has a skirt 18 which seats around the 
periphery of the plate 16 to be secured by bolts 19. It thus forms a 
shallow chamber with the plate 16, but projecting outwardly from it are 
two parallel, hollow cylindrical formations 20 and 21. These are, in 
effect, fixed pins on which the drums 1 and 2 are respectively journalled 
by double roller bearings 22 and 23. The axial centre of each of these 
bearings is approximately one third of the axial distance of the 
associated drum from that end of the drum nearest the base, which is where 
the first turn of the cable is taken. Since the load is much greater at 
that end, and decreases progressively towards the other end, the centroid 
of the load will be off centre towards the base. By positioning the 
bearings of the drums to embrace that centroid, there is no need to 
provide bearings at the ends. This is simple and economical and 
facilitates the arrangement of the gear system to be described. 
The drive is applied from a stub shaft 24 which is splined into the hollow 
end of a main drive shaft 25, the two shafts being secured against mutual 
axial movement by a transverse pin 26. Near the other end of the shaft 25 
a pinion 27 is formed, which provides the sun gear of an epicyclic train. 
Planets 28 (only one of which is shown) are carried by an end plate 29 
secured to drum 1 by bolts 30. Each planet is mounted on a flexible stud 
assembly 31 through needle bearings 32. Each flexible stud assembly 
consists of a pin 33 projecting inwardly from the carrier plate 29 and 
formed with a neck or reduced diameter portion towards its free end. A 
sleeve 34 is fitted to the extreme end of th pin and is cantilevered back 
towards the plate 29. The flexibility that this provides allows for 
automatic load sharing in accordance with known techniques. 
The annulus 35 for the epicyclic is a large diameter portion of a stepped 
tubular member 36, whose lesser diameter portion extends from the 
epicyclic back towards the base plate 16, surrounding the shaft 25 and 
within the cylindrical formation 20 of the body 17. At an intermediate 
point it is journalled within that formation 20 by a roller bearing 37. 
The end of the sleeve member 36 adjacent the base is externally splined, 
and is thereby united to a gear 38. This gear is rotatably supported by a 
ball journal bearing 39 and it rotates within one end of the shallow 
chamber formed by the body 17 and its base plate 16. 
The gear 38 meshes with another gear 40 rotatably supported at the other 
end of the chamber by a further ball journal bearing 41. The gear 40 is 
formed at one end of a hollow cylindrical member 42 which extends freely 
through the cylindrical formation 21 to terminate adjacent a plate 43 
secured by bolts 44 to the end of the drum 2. This other end of the member 
42 is externally splined to engage splines on the inside of an annular rib 
formation 45 on the inside of the drum end plate 43. 
In operation, the drum 1 will be driven in unison with the planet carrier 
29, the orbiting of the planets being determined by the drive from the sun 
27 and the reaction provided by the annulus 35. The latter is positively 
coupled via 36, 38, 40, 42, 45 and 43 to the drum 2. Thus there is a 
differential coupling between the two drums. It follows that from the 
single input there is twice the gear ratio that would be obtainable by 
simply duplicating the epicyclic gear system for each drum and having two 
fixed annuli, while the torque on the pinion 27 will only be half what it 
would be with such an arrangement, although it will have to rotate at 
twice the speed to achieve the same rate of winding. 
It will be understood that it is not essential to have the gears 38 and 40 
of equal size. According to the application intended, the friction and 
loads expected, various gear ratios can be employed. It is not even 
essential to have drums of similar size. 
The winch of FIG. 4 operates on the same principles but with a different 
position of the epicyclic and the addition of a reduction gear which 
enables a much higher speed driving motor to be used. The epicyclic is no 
longer inside one of the drums (still referenced 1 and 2) and so more 
flexibility is possible in its design, since it is not constrained in 
volume. Also, the drums can now be made substantially the same, giving 
some economy. 
In more detail, the drive is applied to a pinion 50 which meshes with a 
large diameter gear 51 journalled to the base plate and fitted to a short 
shaft 52 whose intermediate portion forms the sun 53 of an epicyclic gear 
train. One of the planets is indicated at 54 and its mounting to a carrier 
55 is similar to the arrangement of FIG. 3. The carrier 55 is a disc-like 
portion at the end of a shaft 56, which at one end rotatably receives the 
free end of the shaft 52, and which at the other end is splined to a 
member 57 forming part of the first grooved drum 1. The other drum part is 
indicated at 58. Therefore this drum is effectively integral with the 
planet carrier of the epicyclic. 
The annulus 59 of the epicyclic is journalled on part of the base body, and 
meshes with a gear 60 fixed to one end of a shaft 61 splined at its other 
end to part of the second drum 2. Thus, this second drum is effectively in 
mesh with the annulus of the epicyclic, and there is the same kind of 
differential coupling of the drums as in FIG. 3. 
It will be seen that the drums are again journalled at an intermediate 
zone, offset towards one end. There are certain detailed differences of 
construction, such a the formation of the base body in several parts, and 
in the provision of a casing over the drums, but these will be evident by 
inspection of the FIG.