Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B23/00—Equipment for handling lifeboats or the like
  • B63B23/02—Davits, i.e. devices having arms for lowering boats by cables or the like
  • B63B23/04—Davits, i.e. devices having arms for lowering boats by cables or the like with arms pivoting on substantially horizontal axes, e.g. gravity type
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B23/00—Equipment for handling lifeboats or the like
  • B63B23/40—Use of lowering or hoisting gear
  • B63B23/58—Use of lowering or hoisting gear with tackle engaging or release gear

Definitions

• This invention relates to a locking device for gravity davits of the type comprising a main arm and a rocking arm which is pivotable about a horizontal axis on the main arm and at its outer end is provided with one or more pulleys- for a hoisting rope serving to launch a lifeboat, raft or the like.
• the device is based on a pivotable locking piece, in contrast to previously known fixed locking pieces, which necessi tate a significant angular movement of the outer davit part in relation to the horizontal plane, when being swung out from stowed position to launching position.
• the problem solved by this invention thus primarily is the one being present with gravity davits in which the hoisting rope arrangement must be secured and relieved in the stowed (inboard) position of the davit, as this securing should be released automatically before launching of the lifeboat, life raft or the like when the davit has reached the outboard position.
• a locking piece is pivotable through a certain angle about a horizontal axis in relation to the rocking arm, that between pivot points on the main arm and the locking piece respectively, there is provided a linkage comprising a locking rod, a second " rod and an intermediate rocking piece which is two-armed and journalled about an axis being fixed in relation to the rocking arm, that the locking rod has a longitudinal guide for a slide member provided on one arm of the rocking piece, that the locking rod further has a longitu ⁇ dinal engagement surface adapted to co-operate with a stop member in a first locking position, and that the end of the locking rod at the rocking piece is adapted to co-operate with a stop member serving to put the locking rod under compressive stress in a second locking position, in which the angle between the main arm and the rocking arm is changed in relation to the angle in the first locking position.
• the invention also involves the substantial advantage that when the davit has been fully swung out, the rocking arm is locked in a fixed angular position in relation to the main arm, without any risk of angle changes which might lead to problems during launching, possibly the hoisting up of a lifeboat. Besides, this angular fixing is automatically released when the hoisting rope arrangement, possibly with a lifeboat or the like, is fully hoisted up to its upper position underneath a davit in its outboard position.
• Fig.l shows the upper parts of a gravity davit with the main arm and the rocking arm in stowed (inboard) position
• Fig.2 shows the arrangement of fig.l in fully outboard position (launching position),
• Fig.3 shows a second embodiment of a similar gravity davit as in fig.l and 2, in stowed position, and
• Fig.4 shows the arrangement of fig.3 in outboard position.
• a rocking arm 2 which is pivotably supported at 9 on top of a main arm 1 being shown only in part.
• a tension rod 3 which is incorporated into the supporting main structure of the davit.
• a hoisting rope arrangement (not shown) with pulleys and so on belonging thereto.
• a pulley 17 which in the case of a rope arrangement having a number of rope parts (multiple tackle) can be several pulleys side by side.
• a movable block 19 which may be incorporated in a hoisting rope arrangement in a usual manner.
• a locking piece 10 is mounted pivotably about an axle 10A which can possibly also be the axle for the pulley 17. As seen in particular from fig.l the locking piece has a projection IOC which can enter into an opening in the block 19 when being in it fully elevated position, so that the whole hoisting rope arange- ent is secured and the rope is relieved of the weight of the suspended lifeboat or the like.
• the locking piece 10 has an arm 10E which at a pivot 10B is connected to a rod 7. At its opposite end this rod is articulatively connected to the outer end of an arm 12D on a rocking piece which is pivotable about an axle 13 and has a second arm 12A forming an angle to the arm 12B.
• the angle between the two arms of the rocking piece is chosen with due consideration to the geometry and otherwise the dimensions of the linkage connecting the pivot 10B on the locking piece 10 to a pivot 5 on the main arm 1.
• the linkage further comprises a locking rod 6 having one end connected to said pivot 5 on the main arm, whereas the opposite end of this locking rod 6 has a particular design for co-opera ⁇ tion with the rocking piece 12A, 12B and elements associated therewith, for bringing about the two specific locking functions mentioned above, in a first locking position and a second lockin position, respectively.
• the rocking piece In the first locking position which corresponds to the stowed position as shown in fig.l, the rocking piece assumes an angular position being rotated to a maximum in the clockwise direction, whereby the arm 12B lies more or less in the prolonga ⁇ tion of the rod 7.
• a pin 14 on the arm 12A is located adjacent the inner end of a slot 16 in the locking rod 6, whereas an engagement surface 6A on the underside of the locking rod 6 engages a stop member in the form of a rotatable sleeve 15 on the axle 13.
• the load is thereby secured or locked, i.e. because the movable block 19 is prevented from being lowered since the projection IOC on the locking piece 10 enters an opening in the block 19.
• the load will tend to press the locking piece in the clockwise direction and thereby give a compressive force in the rod 7.
• the rocking piece arm 12B has such a .direction that the point of connection between this arm and the rod 7 lies somewhat above the dead point in relation to the compressive force mentioned, the rocking piece will be urged in the anti-clockwise direction as indicated with the arrow in fig.l.
• the rocking piece and therefore the complete linkage is blocked against movement in this locking position because of the pin 14 in the slot 16 and the engagement between the surface 6A and the sleeve shaped stop member 15.
• the davit When the lifeboat shall be launched from a starting point i the stowed position of the davit as shown in fig.l, the davit must first be swung out. During this outboard movement the angl between the main arm 1 and the rocking arm 2 will be changed so that the locking rod 6 is retracted in a direction away from the rocking piece 12A, 12B, the pin 14 sliding in the slot 16 toward the opposite end thereof at the same time as the engagement surface 6A on the underside of the locking rod 6 is displaced in the lefthand direction in fig.l in relation to the stop sleeve 15.
• the pin 14 can be regarded as a slide member which can be moved in the longitudinal direction of the locking rod 7 in a guide formed by the slot 16.
• this sleeve also in this locking position constitutes a stop member in co-operation with the locking rod 6. If under some form of influence the rocking arm 2 should have a tendency to move downwards with its outer end in the direction of an angular position in relation to the main arm as in fig.l, the locking rod 6 will be put under compressive stress and thereby block the whole linkage so that the angular position shown in fig.2 is fixed.
• This locked position means a safe launching, or possibly elevating of a lifeboat, and this position is maintained until it may be terminated by operation of the davit for this purpose, in particular by hoisting up the movable block 19 so that this again enters into co-operation with the locking piece 10 and swings this back upwards to the position shown in fig.l.
• the locking piece 10 is provided with a projecting nose 10D which catches the upper side of the block 19 at the termina ⁇ tion of the hoisting movement and gives the above swinging-up of the locking piece 10.
• the sleeve 15 on the axle 13 has a dual stop function namely against the engagement surface 6A on the underside of the locking rod 6, and against the end of this rod respectively.
• the sleeve 15 on the axle 13 has a dual stop function namely against the engagement surface 6A on the underside of the locking rod 6, and against the end of this rod respectively.
• a linkage which can be regarded as inverted in compari ⁇ son to the arrangement of fig.l and 2, concerning the angular movement of the davit's main arm 21 and the rocking arm 22 when moving from the stowed position (fig.3) to the launching position (fig.4).
• a linkage consisting of a locking rod 26, a rocking piece 32A, 32B and a rod 27 which is much shorter than the rod 7 in fig.l and 2. Another difference can be seen in the angular relationship between the two arms 32A and 32B of the rocking piece.
• the locking rod 26 has a shorter slot 36 and a shorter engagement surface 36A than the corresponding elements of the locking rod 6 in fig.l and 2.
• an axle 33 for the rocking piece and a rotatable sleeve 35 on the axle are designed in full analogy with the corresponding parts in the first embodiment described above.
• the arm ratio of the locking piece i.e. the distance between the supporting point 20A and the pivot 20B for connection to the rod 26, is relativel shorter than in the first embodiment, in which a more characteri ⁇ stic and mainly downward extending arm gives a longer distance between the bearing 10A and the pivot 10B.
• the embodiment of fig.l and 2 can be regarded as more suitable for large loads than the embodiment of fig.3 and 4.
• the first locking position described above thus corresponds to the fully outboard position of the davit in the second embodiment as shown * in fig.4.
• the second locking position described is represented by fig.3, i.e. the stowed position of the davit, in which the end of the locking rod 36 is abutting against the righthand side of the sleeve 35.
• linkages having the fundamental function comprising rods and a rocking piece as discussed above with reference to the figures of drawings, in practice can be designed in various ways, for example by having the various parts which are included, arranged more or less in the same plane, or they may be duplicated in parallel ("twin rods") and with different forms of guide, slide and stop members which in the principle have similar functions as the structural features being specifically described.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Clamps And Clips (AREA)
• Emergency Lowering Means (AREA)
• Treatment Of Sludge (AREA)
• Load-Engaging Elements For Cranes (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19889986

Family Applications (1)

Country Status (5)

Cited By (4)

Citations (2)

• 1987
  • 1987-06-01 NO NO872294A patent/NO162450C/no unknown
  • 1987-07-13 FI FI873090A patent/FI873090A/fi not_active IP Right Cessation
• 1988
  • 1988-05-16 WO PCT/NO1988/000044 patent/WO1988009741A1/en unknown
  • 1988-05-16 AU AU17842/88A patent/AU1784288A/en not_active Abandoned
  • 1988-05-31 ES ES8801715A patent/ES2008802A6/es not_active Expired

Patent Citations (2)

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