Hydraulic turning gear

A hydraulic turning gear for imparting rotational movement to a rotor comprising:

• a ratchet wheel for attachment to the rotor;
• a pawl mechanism for engaging the ratchet wheel;
• a hydraulic cylinder connected to the pawl mechanism causing the pawl mechanism to reciprocate whereby the linear movement of the pawl mechanism causes the ratchet wheel to rotate;
• a source of relatively low pressure hydraulic fluid for driving the hydraulic cylinder;
• a booster cylinder for raising the pressure of the relatively low pressure fluid to a higher pressure sufficient to drive the hydraulic cylinder;
• the booster cylinder being connected to the hydraulic cylinder;
• and,
• valve means for directing the relatively low pressure hydraulic fluid to drive the booster cylinder, and
• wherein the hydraulic cylinder includes an arm which extends externally from the hydraulic cylinder and the pawl mechanism includes a clevis which is mounted to the hydraulic cylinder arm and a pawl which is pivotally attached to the clevis, and said hydraulic gear further comprising:
• a pin attaching the pawl pivotally to the clevis;
• a plurality of stacked Belleville washers for provding a variable frictional force between the pawl and the clevis;
• a stationary guide rail for guiding the linear path of the pawl mechanism including the clevis;
• the guide rail also contacting the pawl to move it from a pivoted positon to a reset position.

A hydraulic turning gear form imparting rotational movement to a rotor comprising:

• a ratchet wheel for attachment to a rotor;
• a pawl mechanism including a pawl element movable between ratchet wheel aligned and ratchet wheel disengagement positions;
• hydraulic means including a piston rod for linearly moving said pawl mechanism toward and away from said ratchet wheel, said pawl element operatively connected by pin means to one end of said piston rod for pivotal movement relative to said piston rod, said pawl element being operable to engage and rotate said ratchet wheel upon extension of said piston rod with the pawl element in the ratchet wheel aligned position;
• and
• adjustable friction means mounted on said pin means for holding said pawl element in said ratchet wheel disengagement position.

A hydraulic turning gear comprising:

• a ratchet wheel for attachment to a turbine rotor;
• a pawl mechanism for selectively engaging the ratchet wheel, the pawl mechanism operating in a linear reciprocating manner;
• a hydraulic cylinder attached to the pawl mechanism;
• a hydraulic booster cylinder fluidly connected to the hydraulic cylinder for supplying high pressure fluid to the hydraulic cylinder;
• a spool valve having two operating positions for supplying low pressure fluid to the hydraulic booster cylinder whereby the hydraulic booster cylinder moves in a reciprocating manner;
• and,
• a pilot valve for positioning the spool valve, the pilot valve and the spool valve being connected to a source of low pressure hydraulic fluid.

A hydraulic turning gear comprising:

• a ratchet wheel attachable to a rotor;
• a hydraulic cylinder having a piston mounted within the hydrualic cylinder and a piston rod extending outside the hydraulic cylinder;
• a pawl mechanism including a pawl and clevis mounted to the piston rod;
• the pawl being pivotally mounted to the clevis with an adjustable friction force therebetween;
• a guide rail mounted to the hydraulic cylinder and the clevis being slidable with respect to the guide rail whereby the pivotal pawl is pivoted away from the ratchet wheel after initial contact therewith and is reset by the guide rail.