Hoist apparatus with dual mast structure and compound power transmission system

Hoist apparatus for lifting a length of pipe comprising:

• a base platform;
• a first mast structure secured to the base platform and projecting vertically therefrom;
• a second mast structure secured to the base platform and projecting vertically therefrom, the second mast structure being laterally spaced from the first mast structure thereby defining a vertically extending pipe handling zone intermediate the first and second mast structures;
• crown sheave means mounted on the upper end of the first and second mast structures;
• traveling sheave means mounted for vertical movement along each of the first and second mast structures;
• a traveling block disposed intermediate the first and second mast structures for movement through the pipe handling zone,
• a first plurality of hydraulic actuators disposed intermediate the traveling sheave means and the upper end of the first mast structure, each of the hydraulic actuators including a piston rod and a cylinder, the piston rods being mechanically secured to the upper end of the first mast structure, and the cylinders being mechanically coupled to each other and to the traveling sheave means;
• a second plurality of hydraulic actuators disposed intermediate the traveling sheave means and the upper end of the second mast structure, each of the hydraulic actuators including a piston rod and a cylinder, the piston rod of each actuator being secured to the upper end of the second mast structure, and the cylinders being mechanically coupled to each other and to the traveling sheave means;
• and,
• cable means having end portions secured to the traveling block and intermediate portions in cooperative reeved engagement with the traveling sheave means and crown sheave means of each mast structure for displacing the traveling block vertically through the traveling zone in a first vertical direction in response to movement of the cylinders in extension along the piston rods.

Hoist apparatus comprising:

• a first mast structure;
• a second mast structure laterally spaced from the first mast structure thereby defining a vertically extending pipe handling zone intermediate the first and second mast structures;
• a crown block interconnecting the upper ends of the first and second mast structures;
• a traveling block disposed beneath the crown block intermediate the first and second mast structures for movement through the pipe handling zone;
• crown sheave means mounted on the crown block and on the upper end of each mast structure;
• traveling sheave means mounted for movement along each of the mast structures;
• a first linear actuator interconnecting the upper end of the first mast structure and the traveling sheave means of the first mast structure for applying a displacing force between the upper end of the first mast structure and the traveling sheave means thereof;
• a second linear actuator interconnecting the upper end of the second mast structure and the traveling sheave means of the second mast structure for applying a displacing force between the upper end of the second mast structure and the traveling sheave means thereof;
• and,
• cable means having end portions secured to the traveling block and intermediate portions disposed in reeved engagement with the traveling sheave means and with the crown sheave means for transmitting the displacing forces to the traveling block.

Hoist apparatus comprising:

• a first vertical mast structure;
• a second vertical mast structure;
• a base platform interconnecting the lower end portions of the first and second mast structures;
• a crown block interconnecting the upper end portions of the first and second mast structures;
• a traveling block disposed for vertical travel intermediate the first and second mast structures;
• a first linear actuator secured to the first mast structure and having a section extendable along the mast;
• a second linear actuator secured to the second mast structure and having a section extendable along the mast;
• first traveling sheave means including a pair of sheaves mounted on the opposite sides of the extendable section of the first linear actuator;
• second traveling sheave means including a pair of sheaves mounted on the opposite sides of the extendable section of the second linear actuator;
• drawdown traveling sheave means including a sheve mounted on each of the extendable sections of the first and second linear actuators, respectively;
• first crown sheave means including a pair of sheaves mounted on the first mast structure, the sheaves being balanced relative to the longitudinal axis of the first linear actuator;
• second crown sheave means including a pair of sheaves mounted on opposite sides of the second mast structure, the sheaves being balanced relative to the longitudinal axis of the second linear actuator;
• crown block sheave means including a pair of sheaves mounted on the crown block at laterally spaced positions intermediate the first and second mast structures;
• first and second equalizing means secured to the first and second mast structures at a predetermined elevation with respect to the base platform, respectively;
• base sheave means including a pair of sheaves mounted on the base platform beneath the traveling block;
• first power transmission means including a continuous cable having first and second terminal portions secured to the traveling block and having a first intermediate portion extending from the first terminal portion reeved successively around a selected one of the crown block sheaves of the crown block, around one of the crown sheaves of the first mast structure, and around one of the traveling sheaves mounted on the first linear actuator, and having a second intermediate portion extending from the second terminal portion reeved successively around the remaining crown sheave and traveling sheave of the first mast structure in parallel with the first intermediate portion, the union of the first and second intermediate cable portions being reeved around the first equalizing means thereby defining a first cable purchase;
• second power transmission means including a continuous cable having first and second terminal portions secured to the traveling block and having a first intermediate portion extending from the first terminal portion reeved successively around the remaining one of the crown block sheaves, around a selected one of the crown sheaves of the second mast structure, the around one of the traveling sheaves mounted on the second linear actuator, and having a second intermediate portion extending from the second terminal portion reeved successively around the remaining crown sheave and traveling sheave of the second mast structure in parallel with the first intermediate portion, the union of the first and second intermediate cable portions being reeved around the second equilizing means thereby defining a second cable purchase;
• and,
• drawdown cable means including first and second drawdown cables each having a first end portion connected to the traveling block, a second end portion secured to the base platform, and an intermediate portion reeved successively around a selected one of the base sheaves and the drawdown traveling sheave of the first and second mast structures, respectively.