US2757847A - Lowering and raising gear for ships' accommodation ladders - Google Patents

Description

Aug. 7, 1956 H. G. TAYLOR 2,757,847

LOWERING AND RAISING GEAR FOR SHIPS ACCOMMODATION LADDERS Filed June 1, 1955 5 Sheets-Sheet 1 Attorney;

H. G. TAYLOR 2,757,847

LOWERING AND RAISING GEAR FOR saws ACCOMMODATION LADDERS Aug. 7, 1956 5 Sheets-Sheet 2 riled June 1, 1955 FlG.2-.

Inventor W 2112 5.,

B $4... 10%, Attorneys Aug. 7, 1956 H. e. TAYLOR 2,

LOWERING AND RAISING GEAR FOR saws ACCOMMODATION LADDERS Filed June 1, 1955 a Sheets-Sheet s Inventor W g. f By Attorneys United States Patent LOWERING AND RAISING GEAR FOR SHIPS AC COMh/IODATION LADDERS Humphrey G. Taylor, Lower Penn, near Wolverhampton,

Englan Application June 1,1955, Serial No. 512,521 Claims priority, application Great Britain June 25, 1954 '3 Claims. (Cl. 228-54) This invention relates to lowering and raising gear for ships accommodation ladders of the slidably or telescopically collapsible type which require to be lowered bodily in the collapsed and substantially horizontalstate from a stowed position to a position in which that end of the ladder which is to be the upper end when in use is held stationary or pivotally supported, say by a foyer platform of the ship, whilst the other end continues to be lowered until the ladder takes up a predetermined inclined position, and then to be extended as may be necessary or convenient for the disembarking or taking on of passengers or personnel.

Accommodation ladders of this type are generally operated by davits and winch gear for paying out and winding in the lower end falls and the upper end falls, the inclined position of the ladder usually being determined by pendants connecting the ladder to an anchorage on the davit, which pendants assist in supporting the load and minimise flexing or bending of the extended ladder when in its inclined position.

According to the present invention, lowering and raising gear, for ships accommodation ladders of the type referred to, comprises two winch drums which are driven simultaneously and respectively control ladder lower end falls and ladder upper end falls, and said gear is characterised in that, whereas the lower end fall drum is directly and positively driven in both directions of rotation, the upper end falls drum is driven through the medium of clutch mechanism, which clutch mechanism automatically disengages or slips when said drum is held against turning as a result of the upper end falls being fully payed out.

An embodiment of the invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a diagram illustrating the principle of the invention.

Fig. 2 is a side elevation of the lowering and raising gear.

Fig. 3 is a sectional view taken on the line 3-3 of Fig. 2, but to an enlarged scale.

Referring to Fig. 1 of the drawings, a common driving shaft carries three winch drums 11, 12 and 13 respectively. The shaft 10 is driven in opposite directions of rotation so as to both raise and lower an accommodation ladder, which comprises upper and lower relatively slidable sections 14, 15, respectively and is depicted in the diagram as in its inclined and extended position of use.

The drum 11 is rigidly secured to the driving shaft 10 so as to be directly and positively driven thereby in both directions, and upon this drum 10 are wound the two lower end falls 16 one for each side of the ladder, which falls 16 both support the lower end of the lower ladder section and control its sliding movement relative to the upper ladder section 14. In this latter connection it can be seen in Fig. 1 that a fall 16 passes around a pulley 17 which pendant ropes 19 are secured to anchorage points at opposite sides of the lower end of the upper ladder section 14, one of which anchorage points can be seen at 20.

Similarly the drum 13 has two upper end falls 21 wound thereon, which falls 21 are secured to anchorage points, one of which is seen at 22, at opposite sides of the upper end of the upper ladder section 14.

The drum 12 is freely rotatable upon the shaft 10, but is coupled thereto by a plate-type friction clutch mechanism indicated diagrammatically at 23.

The drum 13 is rotatable about the shaft 10 and is also axially movable along it, having a screw-threaded engagement therewith indicated at 24, the drum 13 being couplable with the shaft 10 by means of a one-way dog clutch mechanism indicated diagrammatically at 25.

It will be understood that the falls 16, 21 and pendant ropes 19 pass over the usual davit arms (not shown).

The arrangement is such that during the initial lowering of the ladder, bodily and in a collapsed and substantially horizontal state, from its stowed position on one deck of a ship to a lower deck at which the upper end of the ladder becomes stationarily held or pivotally supported, both sets of falls 16, 21 are under load and they and the pendant ropes 19 are all payed out, simultaneously and equally, the two clutches 23, 25 being fully engaged and imparting the drive from the shaft 10 to the upper end fall drum 13 and the pendant rope drum 12 respectively. When the upper end of the ladder becomes stationarily held or pivotally supported, say by a foyer platform of the ship, the upper end falls 21 having been fully payed out, and, although relieved of the weight of the ladder, are taut enough to prevent continued rotation of the upper end fall drum 13 to which they are attached, so that the associated clutch 25 automatically disengages as will be explained in detail below. The lower end falls 16 are still under load and they and the pendant ropes 19 continue tobe payed out simultaneously and equally, the pendant drum clutch 23 being still fully engaged, until the pendant ropes 19 become fully payed out and thereby prevent continued rotation of the pendant drum 12 to which they are attached and this causes the associated clutch 23 to commence to slip. The ladder, still in its collapsed state, has now assumed its predetermined inclined position with the fully payed out pendant ropes 19 under load, and continued rotation of the driving shaft 10 and drum 11 pays out the lower end falls 16 so as to lower the slidable or telescopic lower part 15 relative to the upper part 14 of the ladder, in the predetermined incline, until either the ladder has been partially or fully extended as required.

'In collapsing and raising the ladder from its extended and inclined position illustrated to its stowed position above referred to, the operation would be the reverse of that above described, that is to say collapsing of the ladder under the winding in of the lower end falls 16 will take place first, the pendant drum clutch 23 will then couple the drum 12 to the driving shaft 10 and the collapsed ladder will be raised from an inclined to a horizontal position, still under the winding in action of the lower end falls 16, the pendant ropes 19 being wound in simultaneously, and finally the upper fall drum 13 will be coupled through its clutch 25 to the driving shaft 10 and further raising of the horizontal collapsed ladder bodily to the stowage position will take place by the simultaneous winding in of both sets of end falls 16, 21, whilst the pendant ropes 19 continue to be wound in.

Details of construction of a suitable winding gear are shown in Figs. 2 and 3, from which it will be seen that the lower end fall drum 11 is rotatable upon a shaft 26, and the drum 11 has a gear wheel 27 secured thereto.

The pendant ropes drum 12 and the upper end falls drum 13 are both carried by a second shaft 28 to which a further gear wheel 29 is secured. Both the gear wheels 27 and 29 are in mesh with a pinion 3t) secured on the same shaft as the-final gear wheel 31 in a train of gears 32, 33, 34 (Fig. 2), the first gear 34 being on the shaft of a reversing electric driving motor 35. Thus the drum 1]. and the shaft 28 are both positively driven by the electric motor 35 in both directions of rotation.

The pendant ropes drum 12 is freely rotatably mounted at 36 upon the driving shaft 23, but is coupled thereto by a friction clutch mechanism of the rnulti-plate type, comprising a first set of plates 37, splined upon the shaft 28 and carrying friction material 38, and a second set of plates 39, slidable axially upon guide bolts 40 carried by the drum 12, the plates 39 being loaded by compression springs 41.

The loading of the clutch plates by the compression springs 41 is such that when the pendant ropes 19 are taut and prevent further rotation of the drum 12 in the paying-out direction, the clutch mechanism slips and allows the shaft 28 to continue rotating while the drum 12 is stationary. As soon as reverse rotation of the shaft 28 commences however, the clutch mechanism will automatically impart drive to the drum 12 to cause the latter to take up slack and wind in the pendant ropes 19.

The upper end ropes drum 13 is mounted rotatably upon the shaft 28 at 42, and is also free to move axially along the shaft. Secured to the drum is an internally squarethreaded sleeve nut 43, which meshes with a squarethreaded portion 44 of the shaft 28. A dog tooth 45 is secured to the gear wheel 29, and a mating dog tooth 46 is carried by the drum 13, the arrangement of this dog clutch mechanism being such that the tooth 45, which always rotates with the shaft 28, can ratchet past the tooth 46 if the latter be stationary during rotation of the shaft 23 in paying-out direction, but during winding-in the tooth 45 positively engages the tooth 46 to rotate the drum 13 for winding-in the falls.

So long as the drum 13 is paying-out the upper end falls 21 it rotates with the shaft 28, but as soon as the falls 21 are fully payed out and the upper end of the ladder is anchored or pivotally supported, the drum 13 is held against rotation by the falls 21. The square-thread 44, which is a left-hand thread interacts with the now nonrotating nut 43 to move the drum 13 axially along the shaft 28, thus disengaging the dog. clutch teeth 45, 46 entirely from each other. It will be understood that the nut 43 does not run off the thread 44, the ladder being lowered to its position of use before this can occur.

During raising of the ladder, rotation of the shaft in reverse direction re-engages the dog clutch teeth 45, 46 automatically so as to transmit the drive for rotation of the drum 13 in winding-in direction at the appropriate time, i. e. when the ladder has been collapsed and raised to a horizontal position by the drums 11 and 12.

he drums 11, 12 and 13 are housed in an outer casing 47', through apertures 43, 49 in the back of which the falls 16, 21 and ropes 19 pass to their respective drums, and

inspection doors 50 are provided in the front of said casing 47.

The gears 31, 32, 33 and 34 are housed in a gear casing '51, and in Fig. 2 manual electric switches are indicated at 52, with switch-gear box 53, for controlling the motor 35.

In Fig. 3 a limit-switch mechanism is indicated at 54,

which mechanism is operated automatically by rotation of the gear 31, and functions to stop the motor when e. g. the ladder is fully lowered and fully raised.

The invention ensures that the upper end falls 21 do not continue to be payed out after the upper end of the ladder becomes held or pivotally supported by the foyer platform and that they automatically pick up that end of the ladder and carry it up to the stowage position. Similarly the pendant ropes 19 are payed out or wound in as the ladder is lowered or hoisted, so that at all times there are no slack falls or ropes to dispose of.

Where pendants other than ropes which require to be payed out as the ladder is lowered are employed, there would, of course, be no need for the pendants ropes drum and its associated clutch mechanism, and in such an application said drum and clutch mechanism would be omitted and the two end falls drums may be on the same driving shaft.

Having fully described my invention, what I claim and desire to secure by Letters Patent is:

1. Gear for lowering and raising ships accommodation ladders of the type referred to, comprising in combination two winch drums which respectively control ladder lower end falls and ladder upper end falls, driving means common to both drums whereby the latter can be driven simultaneously, the lower end fall drum directly and positively in both directions of rotation, and clutch mechanism which automatically disengages the upper end fall drum from the drive when said latter drum is held against turning as a result of the upper end falls being fully payed out.

2. Gear for lowering and raising ships accommodation ladders as claimed in claim 1, including a driving shaft upon which the upper end falls drum is rotatable, clutch elements associated with said driving shaft and upper end falls drum respectively, and a screw-threaded connection between said driving shaft and said relatively rotatable drum whereby, when the latter is held against rotation by its falls the action of the screw thread, according to the rotation of said driving shaft, will be to move said drum axially along the said driving shaft to effect engagement or disengagement of said clutch elements.

3. Gear for lowering and raising ships accommodation ladders as claimed in claim 1, including a driving shaft upon which the upper end falls drum is rotatable, clutch elements associated with said driving shaft and upper end falls drum respectively, a screw-threaded connection between said driving shaft and said relatively rotatable drum for axially moving the latter to effect engagement or disengagement of the clutch elements, according to the direction of rotation of said shaft, when the said drum is held against rotation by the upper end falls, a further drum also rotatable about said driving shaft and controlling pendant ropes, and friction clutch mechanism which couples the pendant ropes drum to said driving shaft, which friction clutch mechanism is of the axially springloaded plate type and slips when the pendant ropes drum is prevented from rotating by load on the fully payed out pendant ropes but automatically takes up and transmits the drive again when the load on the pendant ropes is relieved during raising of the ladder.

No references cited.

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