US3802575A

US3802575A - Retractable posts

Info

Publication number: US3802575A
Application number: US00267094A
Authority: US
Inventors: D Ingram; K Mitchell
Original assignee: General Electric Company PLC
Current assignee: General Electric Company PLC
Priority date: 1971-07-01
Filing date: 1972-06-28
Publication date: 1974-04-09
Anticipated expiration: 1991-04-09
Also published as: CA944259A; GB1384708A

Abstract

A retractable post assembly incorporates a fluid operated piston and cylinder unit having a pair of pistons located one at each end, one of which pistons controls means for raising or retracting the post, and the other of which controls the operation of a member, such as a swinging arm, movably mounted on the post, so that by feeding fluid into the cylinder the post can first be raised and the movable member then moved from an inoperative to an operative position.

Description

United States Patent 1191 Ingram et a1.

[ Apr. 9, 1974 RETRACTABLE POSTS Inventors: David John Ingram, Barnhurst;

Keith James Mitchell, Higham near Rochester, both of England The General Electric Company Ltd., London, England Filed: June 28, 1972 Appl. No.: 267,094

Foreign Application Priority Data July 1, 1971 Great Assignee:

us. 01 212/64, 212/35 R, 214/13 Int. Cl. B66c 23/02, B66c 23/56, B631) 27/10 Field of Search 212/57, 64, 30-35; 214/13-15; 104/114 References Cited UNITED STATES PATENTS 11/1967 Stonely 214/13 6/1971 Ingram....-... 104/114 2/1967 Goss 9/1969 212/58 Potain .f. 212/57 FOREIGN PATENTS OR APPLICATIONS 113,393 3/1945 Sweden 212/64 53,727 8/1967 Poland 212/57 38,104 6/1956 Poland 212/64 Primary ExaminerRichard E. Aegerter Assistant ExaminerJames W. Miller Attorney, Agent, or Firm-Kirschstein, Kirschstein, Ottinger & Frank [57] ABSTRACT A retractable post assembly incorporates a fluid operated piston and cylinder unit having a pair of pistons located one at each end, one of which pistons controls means for raising or retracting the post, and the other of which controls the operation of a member, such as a swinging arm, movably mounted on the post, so that by feeding fluid into the cylinder the post can first be raised and the movable member then moved from an inoperative to an operative position.

11 Claims, 7 Drawing Figures IWENIEDAPR 9 I974 SHEET 3 UF 4 Fig.3

Fig.4

. 1 RETRACTABLE POSTS This invention relates to retractable posts or masts, and especially, though not exclusively, to such posts or masts, hereinafter referred to simply as posts, which are of the kind designed to carry an end of a cable emtween two stations.

Such a retractable post may, forexample, be

mounted on a ship, for carrying an end of a support post in its raised position. In such an application it is desirable to maintain the end of the support cable at a sufficient height during transfer to allow for the sag'at the centre of the cable, which can in some cases be substantial and may vary considerably where the loads are being transferred between two ships at sea, due to rolling and other movement of the ships, and to variations in the distance between them. To facilitate loading and unloading it has therefore been proposed to secure the end of the cable to a carrier member whichcan be lowered relative to the post, the member being raised to an operative position during an actual transfer operation; such a carrier member conveniently comprises a swinging arm pivoted to the post about a nominally horizontal axis so tha the end of the arm to which the support cable is arranged to be attached can be pivoted downwards to a loading/unloading position, or raised to an operative position as may be required.

An object of the invention is to provide a retractable post suitable for such an application.

According to the invention a retractable post incorporates a fluid operated piston and cylinder unit having a pair of pistons located one at each end, one of which pistons controls means for raising or retracting the post and the other of which controls the operation of a carrier member movably mounted on the post.

The carrier member may comprise a swinging arm as previously described, means being provided for latching the arm in a lowered, inoperative, position substantially parallel to the post to permit the post to be retracted. With such an arrangement the control system is simplified since with the arm latched in its inoperative position by the latching means, which can be of any no kind the admission of the working fluid into the cylinder results in the raising of the post, but has not effect on the arm, but once the post has been raised to its operative position, and the arm unlatched, further admisployed to support a load as the latter is transferred besion of working fluid into an appropriate part of the cylinderwill result in the raising of the arm.

Means. are preferably provided for latching the post in its raisedposition, so that when it is required to raise or lower the arm this. can be simply effected by control of the working fluid, the post being prevented fromretracting by the latching means, which can be of any convenientkind. I

Conveniently the piston that controls the raising and lowering of the post is located at the lower end of the cylinder,- and is in the form of a ram carrying a pulley,

acable havingone end connected to the post assembly and the other end connected to a support member, passing round the pulley to provide a support for the assembly so that as the ram is extended the assembly is 2 raised. The cable conveniently passes around a plurality of other pulleys carried by the assembly in order to magnify the movment of the assembly for a given movement of the ram, thus enabling a relatively large movement of the assembly to be obtained for a relatively small movement of the ram.

The support is conveniently provided by a slewing ring through which the post assembly extends to permit the whole assembly to be rotated about a normallyvertical axis.

Preferably the raising and lowering of i the post and the movement of the arm are controlled by a hydraulic system, the various parts of the system being carried by thepost so that the whole of the post assembly can be removed or replaced as a complete unit for servicing if this becomes necessary.

Conveniently the post assembly is substantially comcable to retractable king posts designed for supporting an end of a cable in 'high line load transfer systems, it will be appreciated thatit may also be used to advantage with retractable posts employed for other purposes.

One embodiment of the invention will now be described by way of example with reference to FIGS. 1 to 7 of the accompanying schematic drawings, in which:

FIG. 1 represents a sectional elevation of a shipmounted retractable king post fitted with a swinging arm designed to carry one end of a cable of a high-line load transfer system,

FIG. 2 represents an elevation of the kingpost in its retracted position,"

FIGS. 3 and 4 represent plan sections along the. lines III III and IV IV of FIG. 1 I FIG. 5 represents a plan view of the kingpost in its raised position,

FIG. 6 represents the hydraulic system employed for raising and lowering the kingpost and swinging arm in diagrammatic form, and

' FIG. 7 shows a modified form of swinging arm.

Thus referring to the drawings the kingpost 1 comprises a pair of broad flanged, essentially vertical beams 2 joined together at the top end by a saddle piece 3 integral with a top trunnion 4.'On this trunnion 4 a boss and lug assembly 5 is provided to enable two tubular steel backstays 6 to be pivotally attached to the trunnion, a hatch cover 30 being rigidly secured to the asv sembly above'the trunnion 4.

14 to one end of the arm 7 so that the other end of the V arm can be raised or lowered under the control of the piston, the latter end of the arm being terminated by eyes to which the jackstay of a high-load transfer system can beattached. The lower end of the cylinder 13 is provided with a further piston 15 in the form of a ram 16 carrying a pulley 17 at its outer extremity as shown. The cylinder barrel is provided at both ends with a normal gland assembly, and in addition is fitted at its lower end with a square section structural steel extension 18 at the bottom of which the unit is pivoted on a bracket 19 attached to the verticalbeams 2. A wire rope 20 is connected to a bracket 21 fixed to the lower end of the cylinder 13, the rope passing around the pulley 17, and around further pulleys 22 mounted on the structural extension, and being connected at its opposite end to a bracket 23 fixed to the underside of a platform 24a carried by a slewing ring 24. The slewing ring is carried by brackets 25 fixed within a short tubular duct 26 which is fitted into an opening in the deck 27, the slewing ring being just below deck level as shown.

The piston 12 controlling the pivoting of the swinging arm 7 is at theupper extremity of its travel when the arm is in its inoperative orstowed position lying parallel to the beams 2 as shown in FIG. 2. When the kingpost is in the retracted position the head of the ram 16 is close to the upper piston 12, and the complete assembly is supported from the hatch cover 30 which rests on the top edge of the duct 26 as shown in FIG. 2, the bottom ends of the beams being secured against transverse movement by a location bracket 31.

A tubular trunkway 32 accommodates the assembly when the latter is in the retracted position.

At the start of an operation hydraulic fluid is admitted to the bottom of the cylinder 13, and the ram 16 is forced downwards out of the cylinder. This has the effect of raising the kingpost assembly out of the trunkway, the hatch cover 30 being lifted with it.

When the assembly reaches the fully raised position, spring loaded latches 29 within the duct automatically engage so as to lock and support the assembly in the raised position; at the same time a limit switch is operated to arrest the motor M driving the reversible constant pressure hydraulic pump P feeding hydraulic fluid into the cylinder 13, and suitable means 35 is operated to release the mechanical latch 36 securing the swinging arm 7' in the stowed position to permit the arm to be raised.-

Raising of the swinging arm 7 is effected by reversing the electric motor M to cause the pump P to supply hydraulic fluid to the end of the cylinder 13, thus forcing the piston 12 downwards and raising the operative end of the arm, openings'33 (FIG. 6) in the head 34 of th ram permitting the hydraulic fluid within the cylinder 13 to be recirculated back to the pump P.

The upper end of the assembly is stabilised against transverse movement by the attachment of the lower end of the backstays 6 to suitably positioned deck cleats 35.

Returning the assembly to its stowed position involves the above sequence in reverse, the latches being retracted by a hand-operated lever (not shown).

The slewing ring enables the whole kingpost assembly to be rotated about a nominally vertical axis to allow for port or starboard rigging, deck cleats being provided in appropriate positions for the backstays. In addition with the backstays fixed to the deck cleats the vertical beams 2, arm 7 and actuating cylinder 13 can be rotated within limits to allow for a t30 station keeping error. To the underside of the support platform carried by the slewing ring there are attached brackets 41 and guide rollers 42 which locate and support the assembly as it is being raised out of the trunkway before the backstays have been secured to their respective deck cleats.

It will be noted that the cylinder unit 13 passes through the slewing ring support platform and is free to tilt as a result of the movement of the swinging arm.

The lower end of the vertical beams 2 are arranged to act as the bedplate for the main hydraulic drive components, namely the motor M with an electro magnetic brake, the pump P as well as hydraulic boost accumulators A, make-up pump MP and tank unit T.

The hydraulic system is shown in diagrammatic form in FIG. 6.

The emergency hand drive E is provided by a hand pump HP together with a directional control'valve DV across the cylinder feed ports.

Electrical connections between the kingpost unit and the trunkway are in the form of a multicore cable loop and control is by pendant normally stored beneath. an access cover (not shown) adjacent the unit. Thus upon removal of the cover the pendant can be lifted out unwinding a trailing cable which is stored on a spring loaded cable reeling drum (also not shown) attached to a suitable mounting bracket.

A power source, which may be an electrically or hydraulically powered motor, may be provided for effecting the rotation of the slewing ring 24. Such a motor may, for example, be mounted outside the tubular duct 26, and be coupled to the ring by gearing, a chain drive or other suitable form of coupling means.

In place of the power pack provided by the motor M and pump P for raising and lowering the kingpost assembly and swinging arm 7 a ring-main hydraulic drive system may be employed, connections from the hydraulic drive system to cylinder 13 being made through suitable couplings and flexible pipes, to allow for the movement of the cylinder in use, of the assembly.

In some cases it may be desirable for the deck to be clear of obstructions when the kingpost assembly is in the retracted position, and in such a case the coaming at the top of the duct 26 may be recessed below the level of the deck so that when the assembly is lowered the upper surface of the hatch cover 30 lies flush with the deck. The deck cleats 35 can also be located in recesses and covered by openable or removable plates lying flush with the deck when not in use.

In an alternative arrangement (FIG. 7) the end of the swinging arm can be constructed as described in United Kingdom Patent Specification No. 1226440 so that during load lowering the effective high point is transferred from the arm attachment point to a point approximately in line with the centre line of the traveller block. Thus the lever arm represented by the distance between these two points is eliminated as the arm comes down and the element of judgement on the part of the operator, otherwise necessary in rough weather conditions, to bring about an impact free landing on the deck of the ship, is no longer required.

We claim:

1. A retractable post assembly for carrying an end of a load-supporting cable comprising:

a post,

a carrier member consisting of a swinging arm pivoted to the post about a nominally horizontal axis having an inoperative position in which it extends downwards substantially parallel to the post to permit the post to be retracted,

means for raising or retracting the post,

a fluid operated piston and cylinder unit having a pair of pistons selectively operable one at each end of the cylinder which is pivoted to the post,

one of which pistons controls said post raising or retracting means, and

the other of which pistons is arranged to raise the arm from an inoperative position to an operative position when the post has been raised from retracted position,

latching means for latching the arm in its inoperative position,

further latching means for latching the post in its raised position, and

means for feeding fluid into the piston and cylinder unitwith the swinging arm latched in its inoperative position, to cause the piston at said one end of the piston and cylinder unit to extend and raise the post, and for subsequently feeding fluid into the opposite end of the piston and cylinder unit with the post latched in the raised position and the swinging arm released, to cause the other piston to retract and thereby raise the arm.

2. A retractable post assembly accordingto claim 1 wherein the piston that controls the raising and lowering of the post is located at the lower end of the cylinder, and is in the form of a ram carrying a pulley, a cable having' one end connected to the post assembly and the other end connected to a support member, passing around the pulley to provide a support for the assembly so that as the ram is extendedthe assembly is raised.

3. A retractable post assembly according to claim 2 wherein the cable passes around a plurality of other pulleys carried by the assembly in order to magnify the movement of the assembly for a given movement of the ram, thus enabling the relatively large movement of the assembly to be obtained for a relatively small movement of the ram.

4. A retractable post assembly according to claim 2 wherein the support is provided by a slewing ring through which the post assembly extends to permit the whole assembly to be rotated about 'a nominally vertical axis.

5. A retractable post assembly according to claim 4 including a power source for effecting the rotation of the slewing ring.

6. A retractable post assembly according to claim 1 wherein the raising and lowering of the post and the movement of the arm are controlled by a hydraulic system, the various parts of the system being carried by the post so that the whole of the post assembly can be removed or replaced as a complete unit.

7. A retractable post assembly according to claim 1 incorporating a hydraulic system for raising and lowering the post and for controlling themovement of the arm, said hydraulic system comprising a reversible constant pressure hydraulic pump arranged to feed hydraulic fluid into the cylinder of the piston and cylinder unit, a reversible electric motor for driving the pump, the motor being energizable to drive the pump in one direction to raise the post with the swinging arm latched in the direction to raise the post with the swinging arm latched in the inoperative position, means for automatically locking the post in the raised position, and for operating a limit switch to dc-energize the motor when the post reaches the fully raised position.

8. A retractable post assembly according to claim 7 including also means for automatically releasing the latch securing the swinging arm in the inoperative position when the post reaches the fully raised position, the motor being energizable in the reverse direction to raise the arm to its operative position.

9. A retractable post assembly according to claim 1 wherein the post is substantially completely retractable below a hatch in a deck, platform or the like and supports at its upper end a hatch cover, so that in the retracted condition the cover closes the hatch opening through which the assembly can be raised.

10. A retractable post assembly according to claim 9 wherein the hatch opening is recessed below the level of the deck, platform or the like so that in the retracted position theupper surface of the cover is substantially flush with the surface of the deck,.platform or the like.

the'pistonand cylinder unit to the system.

Claims

1. A retractable post assembly for carrying an end of a loadsupporting cable comprising: a post, a carrier member consisting of a swinging arm pivoted to the post about a nominally horizontal axis having an inoperative position in which it extends downwards substantially parallel to the post to permit the post to be retracted, means for raising or retracting the post, a fluid operated piston and cylinder unit having a pair of pistons selectively operable one at each end of the cylinder which is pivoted to the post, one of which pistons controls said post raising or retracting means, and the other of which pistons is arranged to raise the arm from an inoperative position to an operative position when the post has been raised from retracted position, latching means for latching the arm in its inoperative position, further latching means for latching the post in its raised position, and means for feeding fluid into the piston and cylinder unit with the swinging arm latched in its inoperative position, to cause the piston at said one end of the piston and cylinder unit to extend and raise the post, and for subsequently feeding fluid into the opposite end of the piston and cylinder unit with the post latched in the raised position and the swinging arm released, to cause the other piston to retract and thereby rAise the arm.

2. A retractable post assembly according to claim 1 wherein the piston that controls the raising and lowering of the post is located at the lower end of the cylinder, and is in the form of a ram carrying a pulley, a cable having one end connected to the post assembly and the other end connected to a support member, passing around the pulley to provide a support for the assembly so that as the ram is extended the assembly is raised.

4. A retractable post assembly according to claim 2 wherein the support is provided by a slewing ring through which the post assembly extends to permit the whole assembly to be rotated about a nominally vertical axis.

7. A retractable post assembly according to claim 1 incorporating a hydraulic system for raising and lowering the post and for controlling the movement of the arm, said hydraulic system comprising a reversible constant pressure hydraulic pump arranged to feed hydraulic fluid into the cylinder of the piston and cylinder unit, a reversible electric motor for driving the pump, the motor being energizable to drive the pump in one direction to raise the post with the swinging arm latched in the direction to raise the post with the swinging arm latched in the inoperative position, means for automatically locking the post in the raised position, and for operating a limit switch to de-energize the motor when the post reaches the fully raised position.

10. A retractable post assembly according to claim 9 wherein the hatch opening is recessed below the level of the deck, platform or the like so that in the retracted position the upper surface of the cover is substantially flush with the surface of the deck, platform or the like.

11. A retractable post assembly according to claim 1 wherein the raising and lowering of the post and the movement of the arm are controlled by an external hydraulic system, and means are provided for connecting the piston and cylinder unit to the system.