A multi-capstan winch has a pair of haulage capstans and at least one delivery capstan associated therewith. In delivering cable to the haulage capstans, the delivery capstan considerably reduces the loading on the cable, thereby allowing haulage capstans of a reduced diameter and weight. The delivery capstan is preferably coaxial with one of the haulage capstans, is a single groove capstan, has a relatively larger diameter than that of the haulage capstans, and has a cable wrap of greater than 180 degrees, but less than 306 degrees, preferably on the order of 220 degrees. Advantageously, the winch is driven by a chain of gears having the majority of the gears being mounted on shafts which lie substantially in a horizontal plane passing through the axes of the capstans.

BACKGROUND OF THE INVENTION 
This invention relates to a multi-capstan haulage winches in general, and 
more specifically to twin-capstan arrangements having a third capstan 
associated therewith for delivering line to the twin capstans. 
U.S. Pat. No. 3,834,673, entitled Twin Capstan Winches, to Alexander 
describes a haulage winch comprising twin haulage drum, i.e. twin, 
multi-groove capstans, and a chain of gears for driving the haulage 
capstans. The majority of the gears are mounted on shafts which lie in or 
are adjacent to a substantially horizontal plane in which the axes of the 
haulage capstans lie. 
Although the described winch is an advance over previous winch designs, 
high bending and compression stresses can occur in the bearings and 
mounting of the haulage capstans. As the diameter of the capstan increases 
for accommodating various cable or line diameters and loading 
requirements, such stresses increase, along with the power supply 
requirements for driving the twin capstans. This not only necessitates a 
more expensive system, but also a more massive system of increased 
dimensions which could pose problems for many applications. 
Because of known advantages over conventional reel-tupe drum winches, the 
twin capstan winches, such as above referenced, have achieved widespread 
usage. For example, in capstan winches, the line progresses smoothly over 
the capstans at a speed determined by the driving motor, as only a single 
layer of line builds on the capstans. The spooling of the line for storage 
is at relatively low tensions, preventing damage to the line even if the 
load varies. Still further, the reeling or storage drum can be constructed 
(or changed) according to the length of the line to be hauled in and may 
also be situated in a convenient place distant from the capstan unit. 
On the other hand, even though a reel-type drum winch may have a tendency 
to crush the line and must be geared to accommodate the maximum torque on 
the outer wrap of the line around its drum, a reel-type winch does not 
require the added expense of a plurality of drum units for implementing an 
effective system. This is a feature which, absent other considerations, is 
believed to heretofore have eliminated any advantages obtained by 
associating a capstan unit with a reel-type drum winch. 
Of course, for certain applications wherein circumstances call for 
independent operation of two separate winding units, a capstan unit may be 
used in association with a reel-type drum winch for achieving the overall 
objective. Such a case is an integrated chain-wire rope mooring system 
wherein a reel-type winch is provided for hauling in and storing the line, 
and a windlass wildcat is provided for hauling in the chain. By operating 
the wildcat when the winch is not hauling in, the chain may be deposited 
in a storage compartment. In such an application, there may be a brief 
period when both the windlass and the winch are hauling in under power; 
since both winch and windlass are already available, the operation of the 
windlass to assist the winch is at no extra system cost. However, it is 
not believed that capstan units have been associated with reel-type drum 
winches primarily for reducing the loading on the reel-type drum winch 
during haul in. The slippage inherent on a capstan type unit, especially 
on a less than full wrap capstan unit, is believed not to have justified 
its use for reducing the loading on a reel-type winch. 
SUMMARY OF THE INVENTION 
An improved winch is provided which utilizes a third or delivery capstan to 
deliver line to a multi-capstan arrangement for reducing the load provided 
to the multi-capstan arrangement, thereby allowing less massive and 
reduced-in-size capstans to be utilized in the multi-capstan arrangement. 
By providing a wrap of the line around the delivery capstan which is 
greater than 180 degrees and less than a full wrap, traction for the 
delivery capstan is increased over a similar arrangement having only a 180 
degree wrap on the delivery capstan; this further reduces the loading on 
the multi-capstan arrangement. By choosing a diameter for the delivery 
capstan of relatively large dimension, a relatively large initial bend 
radius is provided to the line where the load is the greatest, thereby 
assuring against over-stressing of the line. 
In the preferred embodiment the multi-capstan winch includes at least 
first, second, and third rotatably driven capstans. The second and third 
capstans are of a reduced diameter, and the first capstan is of an 
enlarged diameter. The second and third capstan have a plurality of wraps 
of the hauling line, and the first capstan has less than a single full 
wrap but more than an one-half wrap of the hauling line. 
According to a feature of the invention, the angle of the wrap around the 
first capstan is between 190 degrees and 300 degrees, and preferably is 
approximately 220 degrees. 
According to another feature of the invention, the hauling line unimpededly 
runs directly from the first capstan to the second capstan so that the 
first capstan provides the greatest assistance in hauling power to the 
second capstan. 
In yet another aspect of the invention, all of the capstans have co-planer 
axes, and the hauling line initially engages the first capstan on one side 
of the axial plane. The line then disengages from the first capstan on the 
other side of the capstan plane, and engages the second capstan on the one 
side of the plane. Although it is not necessary, preferably the first 
capstan is coaxial with either the second or third capstan. 
According to the method of the invention, line is hauled in using apparatus 
which includes a double capstan winch. The method comprises the steps of: 
(a) Passing the line around a third driven capstan, whereby the angle of 
wrap around the third capstan is greater than one-half a turn but less 
than a full turn; and 
(b) coupling the line from the third capstan to the double capstan winch. 
According to the method of the invention, the angle of wrap around a third 
capstan is within the range of 190 degrees-300 degrees and preferably is 
substantially 220 degrees. Further, the step of coupling preferably 
includes the step of unimpededly passing the line directly between the 
third capstan and the double capstan winch. 
It is accordingly a general object of the present invention to provide a 
new and improved multi-capstan winch which utilizes still another driven 
capstan for achieving a multi-capstan winch of an overall reduced size and 
weight. 
Other objects and features of the present invention will become apparent 
upon a reading a detailed description of a preferred embodiment in 
conjunction with accompanying drawings; wherein:

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring now to FIGS. 1 and 2, one embodiment of a multi-capstan winch 10 
is shown. The haulage winch 10 includes a plurality of driven capstans 12, 
14, 16 which are driven in coordination for accommodating a hauling line 
18 consisting of both chain 20 and cable 22. The capstans 12, 14, 16 have 
substantially parallel, horizontal rotational axes which preferably lie 
substantially in the same plane. 
The capstan 16 is a haulage capstan having a single groove designed to 
accommodate both the chain 20 and the cable 22. The haulage capstan 16 has 
a diameter larger than that of the capstans 12, 14, and is constructed and 
arranged in relation to the capstans, 12, 14 for delivering the line 18 to 
the capstans 12, 14. 
The haulage capstan 16 is disposed substantially at the level of the 
horizontal plane containing the rotational axes of the capstans 12, 14, 
and the rotational axes of the haulage capstan 16 is slightly inclined to 
the horizontal. 
A pair of guide plates 30 are connected to axial housings of the haulage 
capstan 16. The guide plates 30 extend substantially parallel to one 
another on either side of the capstan 16, to a position below the lowest 
portion of the capstan 16. The guide plates 30 are intended to guide the 
chain 20 delivered from the haulage capstan 16 to a chain collecting 
locker 32 disposed beneath the guide plates 30. 
An automatic spooling device 34 for feeding cable from the capstans 12, 14 
to a storage drum (not shown) is disposed above the capstan winch. The 
spooling device 34 and the storage drum are conventional and need not be 
described. For example, a suitable storage drum and a suitable drive 
mechanism 36 for the capstans 12, 14 is described in U.S. Pat. No. 
3,834,673, issued Sept. 10, 1974 to Alexander and assigned to the assignee 
of the present invention. As disclosed in the Alexander patent, the 
capstan winch comprises a chain of reduction gears and at least one bevel 
gear, whereby the axes of rotation of the twin capstan 12, 14 is at right 
angles to the axes of rotation of the power input shaft. The gears are 
housed in a generally L-shaped gearbox having a longer part extending 
parallel to the power input shaft and a shorter part extending at right 
angles to the longer part. The power input shaft extends through one wall 
of a casing of the shorter part of the gearbox. The shorter gearbox part 
includes a number of spur gears and includes provision for selecting 
forward drive of the twin haulage capstans. 
Each capstan is rotatable on a respective shaft to which a spur gear is 
attached, and a main drive shaft lies between the shafts of the twin 
haulage capstans. The main drive shaft carries a spur gear in driving 
contact with both the spur gears on the shafts of the haulage drums. The 
main drive shaft also has a crown gear of a bevel gear secured thereto. 
The shafts of the twin haulage drums, the main drive shaft, and the crown 
wheel are all located in the longer gearbox part, and a connecting shaft 
connects the shorter and longer gearbox parts. One end of the connecting 
shaft lies within the shorter gearbox part and has a spur gear fixedly 
mounted thereon, and the other end of the connecting shaft has bevel 
pinion gear fixedly mounted thereon. The bevel pinion gear meshes with the 
crown gear. 
Further as described in the Alexander patent, the storage drum is driven 
from the gearbox via a friction coupling. The gearing is such that but for 
relative movement, i.e. slipping of the parts of the friction coupling, 
the storage drum would be driven to reel in cables during pulling of a 
load at a higher speed than the cable is reeled in by rotation of the 
haulage drums. 
The storage drive mechanism locks during paying out cable from the drum so 
that the entire rotational movement of the drum during paying out of cable 
occurs by slipping of the friction coupling. The storage drum drive 
mechanism includes a shaft having mounted thereon a chain wheel including 
a free wheel device which locks to drive the chain wheel when the shaft 
rotates in a direction consistent with the reeling in of cable. On the 
other hand, the device free wheels allowing the wheel to remain stationary 
when the shaft rotates in a reverse direction consistent with paying out 
of the cable. 
The chain wheel which includes the free wheel device is drivingly connected 
to a second chain wheel rotatable with a shaft which in turn is rotatable 
with a friction plate arranged in frictional driving contact with the 
storage drum. The shaft to which the friction plate is secured is 
connected with another free wheel device which prevents the shaft from 
rotating in a direction consistent with paying out of the cable from the 
storage drum, whereby such rotation of the drum occurs by slipping of the 
friction coupling. 
In winches to be used for hauling heavy loads, it is preferred not to 
include a bevel gear in the gearbox for driving the twin haulage capstans. 
In this case, the gearbox preferably comprises only spur gears having 
parallel shafts which lie adjacent a substantially horizontal plane in 
which the axis of the twin haulage drums lie. The spur gears may or may 
not be chain driven. 
For further detail of the above-described arrangement, reference is made to 
the Alexander patent, U.S. Pat. No. 3,834,673, which is expressly 
incorporated herein by reference. 
The haulage capstan 16 may be chain driven either from the input shaft from 
the gearbox for the winch or may be independently driven from a motor, 
such as a hydraulic motor, other than that used to drive the input shaft 
to the double capstans. This is schematically shown in FIG. 4 as the drive 
mechanism 36. 
A tripping device (not shown) is disposed between the haulage capstan and 
the capstan 14 which receives the line 18 from the haulage capstan 16. 
When activated, the tripping device cuts off the drive to the storage drum 
and to the capstans 12, 14 but not to the haulage capstan 16. In this 
manner, the chain 20 may be taken up by operation of the haulage capstan 
16 and deposited within the locker 6. 
In more detail, in operation of the winch for raising, for example, an 
anchor attached to an anchor chain which is connected to a cable, the 
cable is hauled in first and passes under and around the haulage capstan 
16 to the top of the capstan 16. From there, the cable passes downwardly 
under the capstan 14 and extends around the capstans 12, 14 several times 
in the grooves thereof. The cable then passes upwardly from the capstan 
12, 14 to the automatic spoolage device 34 which feeds the cable to the 
storage drum. 
Eventually the chain reaches the haulage capstan 16. When the chain first 
passes over the capstan 16 it strikes an obstruction on the tripping 
device which causes the drive to the storage drum and the capstans 12, 14 
to be stopped. However, the haulage capstan 16 continues to rotate and the 
chain passes over the haulage capstan 16 and falls into the storage locker 
32. Owing to the slight inclination of the axes of the haulage capstan 16 
to the horizontal, the part of the chain which falls into the locker 32 
does not interfere with the part of the chain which is being delivered to 
the capstan 16. 
There are other suitable embodiments for depositing the chain 20 into the 
locker 32. One such embodiment merely releases the drive to the storage 
drum. This releases the back tension to the capstans 12, 14 which in turn 
allows the line 18 to disengage from contact with the grooves of the 
capstans, due to the natural elastisity of the wire line. This 
disengagement is an effective clutching which discontinues hauling in of 
the cable 22 during hauling in of the chain 20. This method is 
advantageous in that it simplifies the drive mechanism to the winch 10 by 
obviating the necessity for the above described trip mechanism. 
A winch in accordance with this aspect of the invention has the advantage 
that the bearing loads on the capstans 12, 14 are substantially reduced 
due to the effect of the haulage capstan 16. Reduction of the bearing 
loads enables the size of the components in the twin capstan section and 
the power supply requirements therefore to be reduced for a winch having a 
given maximum load, as compared with a winch comprising twin capstans but 
no haulage capstan associated therewith. 
Further, the use of a leading haulage capstan of large diameter has the 
advantage that the pressure between the cable and the haulage capstan, 
during hauling, can be maintained at a low level. This enables the winch 
10 to be used for hauling relatively inexpensive cables. There is also the 
possibility of using very high strength plastics material cables which, 
when subjected to high compressive stresses on drum winches of the 
standard type tend to be destoyed by being stored on the drum at very high 
pressures. 
Referring now to FIGS. 3 and 4, another embodiment of the multi-capstan 
winch 10 is depicted. In this embodiment, the haulage capstan 16 is 
coaxial with the capstan 14. As seen in FIG. 3, during take up the haulage 
capstan 16 is driven (by equipment not shown but which may be as described 
for the embodiment of FIG. 1) in a rotational direction opposite to that 
of the capstans 12, 14. (Likewise, the tripping device, the storage drum, 
the spooling device and the locker features described with respect to FIG. 
1 may be employed with respect to the winch 10 shown in FIG. 3.) 
As an outstanding feature of the invention, and as is also shown in FIG. 1, 
the line 18 is wrapped around the capstans 12, 14, 16 in a manner to 
effect optimum utilization of the hauling capstan 16 for reducing the load 
on the capstans 12, 14. By reducing the loading on the capstans 12, 14, 
the capstans 12, 14 and associated drive and support equipment such as 
bearings, etc. are advantageously reduced to provide an overall cheaper 
and lighter weight system. 
More specifically, the line 18 is fed to the capstan 16 where it engages 
the capstan 16 at a point A on one side of the coaxial plane. The line 18 
thereupon wraps around the capstan 16 less than a single full wrap, but 
more than an one-half wrap to a point B on the other side of the coaxial 
plane. The angle from the point A to the point B around the capstan 16 is 
between 190 degrees and 300 degrees, and preferably 220 degrees. 
From the point B on the capstan 16, the line 18 is unimpededly passed 
directly to the capstan 12 where it engages the capstan 12 at a point D on 
the one side of the coaxial plane. It is noted that a segment C of the 
line 18 crosses the coaxial plane at a location between the capstans 12, 
14; i.e. there is a crossover of the line 18. 
From the point D, the line 18 wraps around the capstan 12 to a point E on 
the other side of the coaxial plane where it is fed to the capstan 14. The 
value of the angle between the points D and E around the capstan 12 also 
varies between 190 degrees-300 degrees and is preferably 220 degrees. 
After the line 18 is fed to the capstan 14, it is wound around the capstans 
14, 12 a plurality of times, the wrap on each of the capstans 12, 14 being 
approximately 180 degrees due to there being no further crossovers of the 
line 18. 
The size of the capstans 12, 14, 16 and the separation between the capstans 
12, 14, and 16 determine the particular value of the wraparound between 
the points A-B and the points D-E. Capstans of a smaller diameter and 
which are closer together achieve a greater wraparound angle than the 
converse situations. Of course, the greater the angle of wraparound on the 
capstan 16, the greater the load reduction on the capstans 12, 14. 
As an example, assuming wraparounds of 220 degrees between the points A-B 
and D-E, and assuming an initial loading on the line 18 of 100 tons 
applied at the point A, the haulage capstan 16 reduces the load to 
approximately 65 tons on the crossover segment C. Accordingly, the 
relatively smaller-in-diameter capstans 12, 14 need accommodate a 
considerably reduced load. After the 220 degree wrapparound on the capstan 
12, the load is further reduced to approximately 43 tons. It thus will be 
appreciated that the crossover segment C, effecting the increased 
wraparound on the capstan 16, is an outstanding feature which allows the 
capstans 12, 14 to have the respective diameters reduced. 
It is further noted that a capstan 12, 14 diameter to rope diameter ratio 
of 12 is preferred. Use of such a ratio assures that the line 18 will not 
suffer undue stresses when bending around the relatively smaller diameter 
capstans 12, 14. 
Although rather detailed embodiments have beed described, it is understood 
that various modifications to these structures and arrangements will be 
apparent without departing from the spirit and scope of the invention as 
hereinafter claimed.