US3559927A

US3559927A - Helicopter rapid securing device

Info

Publication number: US3559927A
Application number: US806212A
Authority: US
Inventors: Asbjorn Baekken
Original assignee: Fairey Canada Ltd
Current assignee: Fairey Canada Ltd
Priority date: 1968-08-21
Filing date: 1969-03-11
Publication date: 1971-02-02
Anticipated expiration: 1988-02-02
Also published as: GB1275468A

Abstract

An improved probe for mounting on the underside of a helicopter, to be used when landing on the deck of a ship. The ship would be provided with a trap device which grasps the probe and holds it and the helicopter immediately the helicopter touches down. The improved probe is telescopic and has a compression spring at its upper end biassing it downwardly. Below the spring is provided a latch which locks to the probe a haul-down cable extending from the helicopter to the ship.

Description

United States atet lnventor Asbjorn Baekken Dartmouth, Nova Scotia, Canada Appl. No. 806,212 2 Filed Mar. 11, 1969 Patented Feb. 2, 1971 Assignee Fairey Canada Ltd.

Dartmouth, Nova Scotia, Canada a corporation of Canada Priority Aug. 21, 1968 Canada 28,072

HELICOPTER RAPID SECURING DEVICE 13 Claims, 13 Drawing Figs.

US. Cl 244/1 15 Int. Cl B64f 1/12 Field of Search... 244/] 15,

[56] References Cited UNITED STATES PATENTS 3,151,826 10/1964 Michel 244/1 l5 3,303,807 2/1967 Stewart et a1 244/1 lSX Primary ExaminerMilton Buchler Assistant ExaminerPaul E. Sauberer Attorney-Cushman, Darby and Cushman PATENTEU FEB 2 l9?! SHEET 1 BF 6 FIG. 1

IIIVEIWOK Asanmv Burr/15M 85/ CW UM.

flit-411M536 PATENTEHFEB 2mm 3559-927 SHEET 2 or 6 i i D VFEE FIG. 4

INVENTAR Asa-70ml ans/mm PATENTEU FEB 2 I97! SHEET 4 OF 6 JIM- 7' PATENTEU FEB 2 I97! SHEET 5 BF 6 FIG. IO

FIGS) 1 0 W533 3 .70 I (M HELICOPTER RAPID SECURING DEVICE It has been proposed in the copending Canadian Pat. applications Nos. 887,011 and 914,140, in which myself Asbjom Baekken and William G. Stewart are named as the co-inventors application Ser. No. 404,374, filed Oct. l6, l9 64, now US Pat. No. 3,303,807, that a helicopter shall be hauled down onto the deck of a ship at sea by a cable acting against the lift produced by the helicopter rotor. This enables the helicopter to land safely despite pitching of the ship and despite the action of wind on the aircraft. In that proposal, a probe carried by the helicopter is seized in a trap carried by the ship so that once the helicopter has landed it is held firmly against movement relative to the ship, and eventually the trap is used to transport the helicopter bodily into a hangar in which the helicopter is stored.

An object of the present invention is the provision of an improved forrn of probe which is more compact than that described and illustrated in the above-mentioned two patent applications.

The present invention relates to a probe device suitable for mounting on the underside of an aircraft capable of hovering flight, and adapted to be grasped during landing of that aircraft at a landing station by a trap device positioned at that station, the probe device comprising a housing, a cylindrical probe telescopically mounted in the housing and movable axially between a lower extended position in which it extends beyond the bottom of the housing and an upper retracted position in which a large part of the probe is disposed within the housing, a passageway through the center of the probe, compression spring means acting between an upper part of the housing and an abutment on the probe and tending to move the probe towards its extended position, messenger means by which a cable can be drawn up into the probe and latching means carried by and movable with the probe and disposed below the spring means and adapted to engage and retain a complementary fitting at the top of the cable and by which the messenger means is connected to the cable.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a side elevation of a helicopter in the final stages of being winched down onto the deck of a ship;

FIGS. 2 to 7 when arranged one above the other in that order with FIG. 2 at the bottom form a sectional side elevation of the probe shown in FIG. 1;

FIG. 8 is a sectional plan view taken on the line VIII-VIII of FIG. 4;

FIG. 9 is a sectional plan view taken on the line lX-IX of FIG.

FIG. 10 is a sectional plan view taken on the line X-X of FIG. 6;

FIG. 11 is a sectional plan view taken on the line XI-XI of FIG. 6;

FIG. 12 is a sectional aft elevation taken on the line XII-XII of FIG. 6;

FIG. 13 is a sectional side elevation taken on the line XIII-XIII of FIG. 8 and taken in the direction indicated by the arrows, the parts of the mechanism being shown in an altemative limiting position.

Referring to the drawings of the present application, Canadian Pat. application No. 914,140 filed Oct. 16, 1964 in the names of William G. Steward and Asbjom Baekken discloses a system (see FIG. 1) for hauling a helicopter 1 down onto the deck 3 of a ship at sea, the helicopter first picking up by messenger line a cable 5 from the ship flight deck 3 and then, after that cable has been secured to the helicopter, a controller on the ship by means of a constant-tension winch hauling the helicopter down by the cable 5 against the lift of the helicopter rotor until a probe 7 on the underside of the helicopter is clamped within a trap 9 in the present drawing. The trap can then be moved forwardly of the ship (ie in the direction of arrow 12), taking the helicopter with it, into a hangar.

As described in that earlier patent application. an eItJCII'IL motor (not shown) is coupled to the driving shaft of a variable displacement hydraulic pump, connected in closed circuit to a fixed displacement hydraulic motor. Such an arrangement is well known in the art, and commonly makes use of a pump with a tiltable swash plate or, as in the embodiment described, a pump with a fixed swash plate but an adjustable tilt head. The output shaft of this hydraulic motor is connected through a gearbox alternatively either to a drum 15 of a haul-down winch or to a drum 21 of a trap-traversing winch. The present invention does not relate to the trap-traversing winch. which is used merely for moving the trap 9 into and out of the hangar referred to above.

The cable 5 has one end wound on the drum l5 and extends from the winch drum first over pulleys of a rope accumulator 23 and then round a guide sheave 25 and finally over a sheave 27 before passing upwardly through the deck 3 to the helicopter l. The rope accumulator includes a first set of pulleys and a second set of pulleys, the two sets being biased apart by a pneumatic cylinder device 29 which has a force/displacement characteristic such that the force biasing the two sets of pulleys apart increases progressively as the two sets are forced closer together by the tension in the cable 5.

The present invention relates to an improved construction for the probe 7, and FIGS. 2 to 13 show the construction of the probe in detail. The probe includes a tubular probe housing 31 (see FIGS. 3 to 8) and a tubular probe 33 of lesser diameter and arranged to extend telescopically into the housing 31. The lower end of the housing is closed by a plug 34 (see FIG. 3) provided with a metal bearing sleeve 35 axially located by an upper ring 37 engaging a circlip 39 and by a lower ring 41 engaging a circlip 43. This bearing sleeve is resiliently centered by a resilient ring 45 and a dirt-sealing ring 47 carried by sleeve 35 tightly engages the probe 33. The lower end of the probe 33 (see FIG. 2) is provided with a bush 49 which at its lower end carries a concentric and rotatable ring 51, the ring being retained by a spring ring 53 and being formed with castellations 55 which permit the cable 5 to pass laterally from inside of the probe without being crushed between the probe and the ship deck 3.

The upper end of the plug 34 (see FIG. 4) is formed with a radially inwardly extending flange 57 which terminates short of the probe 33 and serves as a stop limiting downward movement of the probe. When the telescopic probe is in its downward limiting position, an upper end of the probe lies a short distance above the flange 57, and locked to this end of the probe is a locking mechanism assembly 59 which also serves to secure to the probe a tubular intermediate extension 61, of lesser diameter than the probe. Near its upper end the probe is formed with a peripheral groove 63 into which are fitted the parts of a segmental junk ring 65. An annular locking mechanism block 67 fits around the tubular extension 61 and butts against both the top of the probe 33 and the top of the junk ring 65, a downwardly extending flange 67A on the block preventing radially outwards displacement of the parts of the junk ring and the block being clamped by bolts 69 to an annular plate 71. Rubber buffer pins 73 fitted in holes in plate 71 are arranged to engage the flange 57 to cushion impact of the plate 71 with the flange.

The annular block 67 is held against rotation in the housing 31 (see FIGS. 4 and 8) by a vertical actuating shaft 75 journaled at its lower end in a needle bearing 77 carried by the flange 57 and joumaled near its upper end (see FIG. 6) in a needle bearing 79 carried by a transverse plate 81 secured by bolts 83 to the housing 31. Block 67 is formed (see FIG. 8) with an annular groove 85 extending into the block from its upper surface and accommodating a rotatable cam member 87. This member 87 is carried (see FIG. 4) by the outer race of a ball bearing 89 the inner race of which is a tight fit on a central boss of the block 67. The top of groove 85 is closed by an annular plate 91 secured to the block 67 by screws 93. A spiral spring 95 has one end located in a hole as shown in the cover plate 91 and has the other end located as shown in a hole in the rotatable member 87. and this spring biases the rotatable member 87 in an anticlockwise direction (viewed as in FIG. 8). Near its lower end. the actuating shaft carries (see FIG. 8) a keyed lever arm 97 provided with a roller 99 at its free end, Roller 99 is disposed in a radial hole 101 in the rotatable cam member 87, the inner part of the block 67 being suitably cut away to permit rotation of the lever arm through an arc to move the cam member between the limiting positions shown respectively in FIGS. 8 and 13. The inner annulus of block 67 is formed (see FIG. 8) with two

radial bores

103 and 105 which accommodate respectively two

clamping members

107 and 109 which at their outer ends are bifurcated to carry rollers 111 and 113. These two rollers engage respectively in two cam slots 115 and 117 in the inner surface of the cam member 87 and the clamping members are also formed with outward extensions which (see FIG. 13) are formed with slots 119 and 121 into which depend tongues 123 and 125 of the cam member. During clockwise rotation of the cam member 87 towards the position shown in FIG. 8, the cam slots 115 and 117 acting on the rollers 111 and 113 move the

clamping members

107 and 109 radially inwards. During anticlockwise rotation of the cam member 87 away from the position shown in FIG. 8, the tongues 123 and 125 act on the radially outer sides of the slots 119 and 121 to move the

clamping members

107 and 109 radially outwards.

Welded to the top of cover plate 91 (see FIG. 4) is a short tube 131 which is concentric with the extension 61 and which at its upper end is welded to an annular ring 133 to form a guide and a stop for the extension 61. In the annular space between the tube 131 and the extension 61 is disposed a sleeve 135 slidably mounted on the extension and having its downward movement limited by a circlip 137 fitted to the extension. A compression spring 139 acts between the ring 133 and a flange 140 on the sleeve 135 and tends to force the sleeve 135 downwards on the extension. One side of the tube 131 is formed with an axial slot 141 through which extends an arm 143 secured to sleeve 135 and engaging a plunger 145 guided in a cylindrical guide 147 mounted on the cover plate 91. The rotatable cam member 87 is formed with an axial hole 149 into which the lower end of plunger 145 can enter to hold the cam member 87 against rotation under the effect of the spring 95. Thus plunger 145 can be left in the position shown to hold the cam member 87 against rotation, but when the probe extension 61 is forced upwards telescopically relative to the block 67, the plunger 145 also moves upwards to free member 87 and so to permit the spring 95 to rotate the cam member 87 and cause the two clamping

members

107 and 109 to move radially inwardly. Only limited upward movement of the extension 61 relative to block 67 can take place before the top of sleeve 135 engages ring 133, so that the lower end of the extension 61 cannot come free from the block. Disposed in an upper end of the guide 147 is indicating member 151 which is moved upwardly through a short distance when the plunger 145 is raised in the above manner. Member 151 is mounted on the lower end of a rod 153 which at its upper end is carried by a plunger 155 (see FIG. 12) slidably mounted in a bush 157 carried by the plate 81. Plunger 155 is formed near its upper end on one side with a cam surface 159 and on its opposite side with a cam surface 161, these cam surfaces acting respectively on the actuating levers 163 and 165 of two

microswitches

167 and 169. A pin 171 acting in a slot 173 of the plunger prevents rotation of the plunger, and springs 175 v and 177 acting against stops on the plunger ensure that stopping of the plunger by the stops takes place progressively. It will be seen that switch 167 provides an indication that the plunger 145 is engaged in the cam member 87 and that switch 169 provides an indication that tubular probe extension 61 has been forced up so that sleeve 135 has butted against the ring 133 and lifted the whole assembly 59.

At its upper end the tubular intermediate extension 61 is fitted (see FIG. 5) within the enlarged bottom end of a tubular upper extension 181, and this enlarged bottom end is provided with two weighted pawls 183 mounted on horizontal pivots and so shaped that a messenger weight indicated diagrammati' cally at 185 can, when lowered through the upper extension 181. rotate those pawls to permit downward passage of the messenger weight, but when subsequently drawn upwardly by a messenger cable 187, is obstructed by the pawls, which cannot rotate in the opposite direction. The upper end of the upper extension 181 diverges upwardly, and fits within a concentric tubular shield 189 (see FIG. 6), which shield is welded to the lower surface of the plate 81. Plate 81 is formed with a central aperture 191 large enough to permit the messenger weight to pass through. A compression spring 193 is disposed in the annular space surrounding the intermediate extension 61 and the upper extension 181, the upper end of this spring being centered by and bearing against a dish 195 bolted to the plate 81 and the lower end of the spring bearing against the top of the cover plate 91. This spring ten to hold the assembly 59, and with it the probe 33, down in a lower limiting position in which the rubber buffers 73 on plate 71 engage the flange 57 and in which the probe extends a considerable distance below the housing 31. When the probe 33 is forced upwardly against the force of spring 193, the assembly 59 also rises until the rim of block 67 reaches the position shown in dotted outline at 678 in FIG. 5, in which it has pressed outwardly a pawl 197 mounted on a pivot pin 199 and biased inwardly of the housing 31 by a compression spring 201, and has become lodged on top of the pawl which then restrains the whole assembly in this raised position.

A bellcrank lever 203 mounted on a pivot pin 205 carries on one arm a pin 206 engaged in a notch in the pawl 197 so that the pawl can be moved outwardly to free the assembly 59 by the action of a cable attached to the other end of the bellcrank and operated from the helicopter cockpit. On top of plate 81 is mounted a hydraulic actuator 209 (see FIG. 11) the ram 207 of which is coupled by a pin 211 to a lever 213 mounted on top of the actuating shaft 75. Pin 211 extends into an arcuate slot 215 in the lever 213, and the arrangement is such that when hydraulic fluid under pressure is supplied through pipe 217 to the actuator 209 the ram 207 is forced to the left thereby turning lever 213 and shaft 75 clockwise (as viewed in FIG. 11) and opening the locks by turning cam 87 anticlockwise (as viewed in FIG. 8) and driving clamping

members

107 and 109 outward. Slot 215 in lever 213 permits manual operation of locks by overriding hydraulic ram 207 when lever through a .cable attachment to its outer hold is moved clockwise.

The messenger weight 185 contains spring-loaded catches adapted to lock onto a bulbous upper end of a coupling 221 secured by a shear pin 223 to the upper end of cable 5.

Considering now the operation of the apparatus, in normal flight the helicopter will leave the probe 33 raised into the housing 31 and held in the raised position by the pawl 197 shown in FIG. 5. As the helicopter approaches =the ship preparatory to landing, the probe 33 is lowered by disengagement of pawl 197 through operation of bellcrank 203 as mentioned above, and by lowering of messenger weight 185. The compression spring 193 ensures that the probe 33 is lowered to its down position. The downward operation of the messenger weight automatically feeds hydraulic fluid through pipe 117 forcing rarn 107 to the right and through the action of pin 211 in the slot 215 moves the lever 213 in a clockwise direction from position as shown in FIG. 11. This movement of the lever through rotation of the shaft 75 and the arm 97 rotates the cam 87 in an anticlockwise direction from the position shown in FIG. 8 to a position in which the clamping

members

107 and 109 are in their outermost positions and the plunger 145 is located in the hole 149 in order to retain the cam member 87 in this position. When the supply of fluid under pressure through pipe 217 is discontinued the ram 207 moves back to its right-hand extreme position, thus moving pin 211 to the right-hand end of slot 115, so that it will not prevent subsequent anticlockwise rotation of the lever 213.

The messenger weight 185 is now lowered by its cable 187 through tubular extension 181, past the pawls 183, through the extension 61, past the clamping

members

107 and 109, and out of the probe 33 to the deck of the ship. On the deck of the ship a member of the ships crew first earths the messenger weight withinsulated tongs to discharge static electricity, and then forces the spring catches in the messenger weight over the bulbous upper end of coupling 221 to couple thecable S to the cable 187. Cable 187 is now wound in on a winch drum carried by the helicopter, and weight 185 is drawn up into the probe 33 until the conical upper surface of the coupling 221 engages the lower end of the tubular extension 61. Continued upwards movement of the messenger weight 185 causes the coupling 221 to raise the tubular extension 61 against the action of the spring 139, so that the arm 143 lifts the plunger 145 and releases the cam member 87. Spring 95 then rotates the cam member so that the two clamping

members

107 and 109 are moved inwardly to their innerlocking positions, the coupling 221 being above these members. As the messenger weight 185 rises still further, the upward movement of the extension 61 is checked by engagement of the upper end of sleeve 135 with the ring 133, and the spring catches in the messenger weight are then forced off the bulbous upper end of coupling 221, which drops back to lie on top of the clamping

members

107 and 109.

The helicopter is now tethered by the cable 5 to the winch on the ship, and the helicopter is drawn down onto the deck of the ship in a controlled manner by the action of the cable acting against the lift produced by the helicopter rotor. When the probe 33 has entered the trap 9, the trap is fired and the helicopter probe is securely held by the trap to hold the helicopter safely despite pitching and rolling of the ship.

When desired, the coupling 221 can be released from the helicopter by the supply of air to the pneumatic actuator 209, the ram 207 then moving to the left to move the lever 213 in a clockwise direction to restore it to its open position, in which the cam member 87 has rotated to move the clamping

members

107 and 109 outwardly, so releasing the coupling 221.

It will be seen that the probe now described and claimed differs from the probes of the two prior patent applications by virtue of its novel arrangement of the spring 193. The overall height is much reduced by the use of latching means which are provided below this spring (instead of above it), since this enables the messenger weight to be accommodated inside the spring rather than above it.

I claim:

1. A probe device suitable for mounting on the underside of an aircraft capable of hovering flight, and adapted to be grasped during landing of that aircraft at a landing station by a trap device positioned at that station, the probe device comprising:

a. a housing;

b. a cylindrical probe telescopically mounted in the housing;

c. the probe being movable axially between a lower extended position in which it extends downwardly below the housing and an upper retracted position in which at least a major part of the probe is disposed within the housing;

d. a passageway extending axially through the probe;

e. an upper part of the housing;

f. an abutment on the probe;

g. compression spring means acting between the said upper part of the housing and the said abutment on the probe and tending to move the probe towards the said lower extended position;

h. messenger cable means carried by the housing and having a coupling by which a haul-down cable can be drawn up by the messenger cable means into the probe; and

i. latching means carried by and movable with the probe, and disposed below the said compression spring means; whereby in use a complementary fitting at an upper end of the said haul-down cable can be latched by the latching means to secure the upper end of the haul-down cable to the probe and thus to the housing and to the aircraft.

2. A probe device according to claim 1, and in which the latching means comprise:

a. an inner guide ring;

radial apertures formed in the inner guide ring.

latch members radially slidable in the said apertures.

an outer cam ring rotatable about the inner guide ring;

cam surfaces formed on the outer cam ring;

f. the cam surfaces being adapted during rotation of the cam ring in a first direction to move the latch members inwardly to engage and to retain the said complementary fitting;

. the cam surfaces being adapted during rotation of the cam ring in the opposite direction to permit outward movement of the latch members to free the said complementary fitting.

3. A probe device according to claim 2, in which the cam ring is also provided with additional cam surfaces, and these cam surfaces are arranged to act on surfaces on the latch members and are effective to move those latch members positively from the latched inwards position to the released outward position during rotation of the cam ring in the said opposite direction.

4. A probe device according to claim 2, and in which:

a. an actuating rod for the cam ring extends axially down one side of, and inside, the housing;

b. a lever is carried by the lower end of the said rod;

c. the cam ring is provided with a slot; and

d. the lever is arranged to engage in the said slot; whereby rotation of the actuating rod effects rotation of the cam ring and thus locking or unlocking of the latching means. A probe device according to claim 2, in which: spring means are arranged to bias the cam ring in such a direction as to cause the latch members to move radially inwardly;

. locking means are arranged to hold the cam ring in position against the action of the spring means; and

c. release means are provided by which the locking means can be rendered ineffective.

6. A probe device according to claim 5, in which:

a. the release means comprise a pin;

b. the pin is movable axially of the probe between a first position and a second position;

c. in the first position the pin locks the cam means to the remainder of the probe; and

in the second position the pin releases the cam means and permits them to be moved by the spring means to move the latch members inwardly to their engaged position.

A probe device according to claim 6, and in which:

an abutment is arranged to be engaged by the said complementary fitting as it rises above a predetermined level in the probe; and

engagement of the abutment by the fitting moves the pin axially to release the cam means.

8. A probe device according to claim 7, and in which:

a. indicating means are associated with the pin; and

b. the indicating means are arranged to provide an indication remotely of the probe that the cam ring is in either of its limiting positions.

9. A probe device according to claim 1, and in which:

a. abutment means are provided in the passageway above the latching means; and

b. the messenger means by engaging these abutments means can be employed to draw the probe upwardly against the action of the compression spring means to its upwardly retracted position.

10. A probe device according to claim 9, and in which:

a. readily releasable holding means are provided in the housing;

b. these holding means are effective to retain the probe in the retracted position; and

c. these holding means can be readily released to permit the probe to assume its extended position.

11. A probe device according to claim 9, and in which the abutment means are so formed that the messenger means can be lowered past the abutment means but are stopped by those abutment means during upward movement.

12. A probe device according to claim 4, and in which:

a power device is disposed in an upper part of the housing; a lost-motion device connects the power device to the actuating rod;

. the power device is effective to rotate the actuating rod to effect rotation of the cam ring and thus unlocking of the latching means;

spring means are arranged to bias the cam ring in such a direction as to tend to cause the latch members to move radially inwardly;

. the lost-motion device is arranged to permit the power device to assume a position corresponding to the locked state of the latching means while the latching means are still held in the unlocked state by the locking device against the action of the spring means; and

the lost-motion device nonetheless permits the spring means to move the latch members radially inwards when the locking device is made inoperative.

13. A probe device according to claim I. and in which:

. these notches are effective firstly to. accommodate without nipping the cable when the probe engages a flat surface; and secondly by rotation of the ring to enable the haul-down cable to extend radially from the probe.

Claims

1. A probe device suitable for mounting on the underside of an aircraft capable of hovering flight, and adapted to be grasped during landing of that aircraft at a landing station by a trap device positioned at that station, the probe device comprising: a. a housing; b. a cylindrical probe telescopically mounted in the housing; c. the probe being movable axially between a lower extended position in which it extends downwardly below the housing and an upper retracted position in which at least a major part of the probe is disposed within the housing; d. a passageway extending axially through the probe; e. an upper part of the housing; f. an abutment on the probe; g. compression spring means acting between the said upper part of the housing and the said abutment on the probe and tending to move the probe towards the said lower extended position; h. messenger cable means carried by the housing and having a coupling by which a haul-down cable can be drawn up by the messenger cable means into the probe; and i. latching means carried by and movable with the probe, and disposed below the said compression spring means; whereby in use a complementary fitting at an upper end of the said hauldown cable can be latched by the latching means to secure the upper end of the haul-down cable to the probe and thus to the housing and to the aircraft.

2. A probe device according to claim 1, and in which the latching means comprise: a. an inner guide ring; b. radial apertures formed in the inner guide ring; c. latch members radially slidable in the said apertures; d. an outer cam ring rotatable about the inner guide ring; e. cam surfaces formed on the outer cam ring; f. the cam surfaces being adapted during rotation of the cam ring in a first direction to move the latch members inwardly to engage and to retain the said complementary fitting; g. the cam surfaces being adapted during rotation of the cam ring in the opposite direction to permit outward movement of the latch members to free the said complementary fitting.

4. A probe device according to claim 2, and in which: a. an actuating rod for the cam ring extends axially down one side of, and inside, the housing; b. a lever is carried by the lower end of the said rod; c. the cam ring is provided with a slot; and d. the lever is arranged to engage in the said slot; whereby rotation of the actuating rod effects rotation of the cam ring and thus locking or unlocking of the latching means.

5. A probe device according to claim 2, in which: a. spring means are arranged to bias the cam ring in such a direction as to cause the latch members to move radially inwardly; b. locking means are arranged to hold the cam ring in position against the action of the spring means; and c. release means are provided by which the locking means can be rendered ineffective.

6. A probe device according to claim 5, in which: a. the release means comprise a pin; b. the pin is movable axially of the probe between a first position and a second position; c. in the first position the pin locks the cam means to the remainder of the probe; and d. in the second position the pin releases the cam means and permits them to be moved by the spring means to move the latch members inwardly to their engaged position.

7. A probe device according to claim 6, and in which: a. an abutment is arranged to be engaged by the said complementary fitting as it rises above a predetermined level in the probe; and b. engagement of the abutment by the fitting moves the pin axially to release the cam means.

8. A probe device according to claim 7, and in which: a. indicating means are associated with the pin; and b. the indicating means are arranged to provide an indication remotely of the probe that the cam ring is in either of its limiting positions.

9. A probe device according to claim 1, and in which: a. abutment means are provided in the passageway above the latching means; and b. the messenger means by engaging these abutments means can be employed to draw the probe upwardly against the action of the compression spring means to its upwardly retracted position.

10. A probe device according to claim 9, and in which: a. readily releasable holding means are provided in the housing; b. these holding means are effective to retain the probe in the retracted position; and c. these holding means can be readily released to permit the probe to assume its extended position.

12. A probe device according to claim 4, and in which: a. a power device is disposed in an upper part of the housing; b. a lost-motion device connects the power device to the actuating rod; c. the power device is effective to rotate the actuating rod to effect rotation of the cam ring and thus unlocking of the latching means; d. spring means are arranged to bias the cam ring in such a direction as to tend to cause the latch members to move radially inwardly; e. the lost-motion device is arranged to permit the power device to assume a position corresponding to the locked state of the latching means while the latching means are still held in the unlocked state by the locking device against the action of the spring means; and f. the lost-motion device nonetheless permits the spring means to move the latch members radially inwards when the locking device is made inoperative.

13. A probe device according to claim 1, and in which: a. a coaxial rotatable ring is provided on the lower end of the probe; b. substantially radial notches are formed in the said ring; c. these notches are distributed about the lower end of the probe; d. these notches have a depth greater than the diameter of the haul-down cable; and e. these notches are effective firstly to accommodate without nipping the cable when the probe engages a flat surface; and secondly by rotation of the ring to enable the haul-down cable to extend radially from the probe.