The vertical adjustment feature of the subject locking mechanism insures accurate and complete alignment of the chock and rack teeth to facilitate lull engagement of the  locking mechanism。

Lateral hydraulic actuation of the chock provides  a first driving force which serves to securely position the chock in engagement and the chock frame is held in a fixed position  for long term  operation by the  provision of mechanical  loclt members。

Horizontal engagement of the chock is maintained by the securing wedge 92 which drives against a compati- ble surface on the chock  and  maintains  the chocl‹ teeth in full engagement with the rack while reacting any couple created on the chock by the force of the rack teeth。

In describing the invention,  reference  has been made to a preferred  embodiment  and  illustrative  advantages of the invention。 Those skilled in the art, however, and familiar with the instant disclosure of the subject inven- tion, may recognize additions, deletions, modifications, substitutions and/or  other  changes  which  will  fall within  the purview  of the subject  invention  and claims。

or  locking  member  70 is fashioned  with  a sloping sur-  45 What  is claimed is:

face 100 designed to cooperate and engage with the wedge 92。 Upon actuation of the motor 96 the wedge cooperates with the sloping surface of the chock to lock the clnoci: into engagement  with  the rack  and  resist the

1。

A jack-up platform locking apparatus for at least partially securing a vertically adjustable leg of an off- shore platform with respect to a deck of the platform, said  locking  apparatus comprising:

tendency of axial forces on the leg to push the chock 70 50 frame means operable to tie securely connected to the

laterally out of engagement with the rack。 While the motor f6 is disclosed as being hydraulic it will be appre- ciated that a mechanical actuation assembly may be substitutecl  by  one of ordinary  skill in the  art。

deck  of the offshore platfo r。m;

lock means having at least one tooth for engaging a compatibly configured surface on the vertically adjustable  leg of  the  offshore platform;

in operation  the platform  is jacked  to its desired  ele-  55 means  for  vertically  adjusting  said  lock  means with

vatioi through the actuation of a pinion  drive assem- blies engaging the rac1‹s 42。 Upon achieving the desired elevation and placement of the chord 34 in a general posture relative to the locking assemblies 50 such that horizontal loading will be directed through the horizon- tal bracing junctions of the 14 chock 70 is vertically adjusted  through  the  provision  of  the  hydraulic motor

$2 until the teeth 72 of the chock are in alignment with the  teeth  in  t!ie  rack  '12。  The actuating  motor  74 then

respect  to said  declt and said  leg;

means for horizontally actuating or deactivating said lock means with respect to said  leg  for engaging and disengaging  said at least one tooth  with respect

6O to the compatibly  configured  surface on said   verti- cally  adjustable leg;

means for vertically securing said lock means with respect  to said deck  and  said leg;  and

means for horizontally  securing said lock  means  with

drix’es  the chock  teeth  72 into firm  and  supporting en-  65