THE DRAWINGS 35

Other objects and advantages of the present invention will become apparent from the following detailed de- scription of a preferred embodiment thereof taken in conjunction  with  the accompanying  drawings, wherein:

FIG。 1is an axonometric view  of a jack-up platform of the type operable to advantageously utilize the sub- ject  locking invention;

FIG。 2 is a plan vie'x of the jack-up  platform depicted

provision  of a plurality of king posts 38。

The platform jacking operation may be achieved by a number of different techniques which are well known in the art。 One form of jacking mechanism for which the subject invention is particularly useful is that known as a rack and pinion jacking or  elevating  mechanism。 In this connection pinion gears 40 extend upon opposite sides of each of the chords 34 and matingly engage with a longitudinally extending rack which is fixedly con- nected  to diametrically  opposed  surface of each  of   the

in FIG。  1 including  the disclosure  of four jack-up  legs  45 chords。   In   operation   the   pinion   gears   are rotated

having  three  chords  each  and  a  plurality  of  intercon-

necting bracing, wherein the platform legs  are  raised and lowered relative to the deck by the provision  of a rack  and  pinion  jacking  units  positioned  at each of the

leg chords; 50

FIG。  3 is  a  detailed  elevational  view  of  a preferred

embodiment of the subject locking mechanism in a dis- engaged  posture;

FIG。 4 is a plan view  of the subject locking  apparatus

as depicted  in  FIG。  3 in a disengaged posture; 55

FIG。  5, note sheet four, is a plan  view  of the  subject

locking apparatus wherein the chock is actuated into an engaged and locked posture with respect to racks ex- tending  upon  either  side of a platform  leg chord;  and

FIG。 6, note sheet three, is a plan view of the subject locking apparatus depicted in FIG。 5 in an engaged posture。

DETAILED DESCRIPTION

Context  of  the Invention 65

Before presenting a detailed description of the subject jack-up platform locking apparatus, it may be worth- while to briefly  outline  the context of the instant  inven-

through hydraulic or  electric  drive  mechanisms mounted on or within the deck and wherein rotation of the pinion in one direction will serve to extend the legs relative to the deck 12 while rotation of the pinion in an opposite direction will serve to retract the legs 14 rela- tive  to  the deck。

LOCKING  APPARATUS

Turning now to the remaining drawings  viz。 FIGS。 3—6, there will be seen a single chord 34 of one of the platform legs 14。 A rack 42 extends longitudinally along and  is fixedly  connected  to  each side of  the chord 34。

The subject invention is directed to a locking mecha- nism 50 which is designed to selectively engage with teeth of the rack 42 and effectively lock  the  deck and legs together in a manner which will be discussed in detail  herein presently。

Each of the jack-up platform lock assemblies 50 in- cludes a frame 52 which is vertically adjustable and guided by pins 54 which are fixedly mounted upon a section 56 of the deck, note FIGS。 4 and 6。 Further in this regard, the frame 52 is provided with vertical ad- justment  guide  loops 58 having  an  elongate  aperture 60