Hydraulic tools having extendable rams for performing various functions such as crimping are described. The tools include a hydraulic system that enables the ram to be rapidly advanced. Methods using the hydraulic systems and tools are also described.

A first piston (4) which is coupled to an output rod (2) and which is inserted in a housing (3) is driven upward by a pressurized fluid. A second piston (6) which is arranged above the first piston (4) is driven downward. This causes a wedge-type force multiplier (M), arranged above the first piston (4), to carry out force multiplication driving with respect to the output rod (2).

A first piston (4) which is coupled to an output rod (2) and which is inserted in a housing (3) is driven upward by a pressurized fluid. A second piston (6) which is arranged above the first piston (4) is driven downward. This causes a wedge-type force multiplier (M), arranged above the first piston (4), to carry out force multiplication driving with respect to the output rod (2).

A system for determining the operability of a valve in active service which provides a user with real time information pertaining to the Safety Margin, the valve torque or thrust, and the percentage of valve MAST that is required for operation. The system employs a combination of an actuator package comprised of a primary actuator, a tandem force module, and a controller operatively connected to the output shaft of the primary actuator, the controller including a processor for calculating the above-described values and providing an output which can be visually, audibly, or electronically observed.

A method of controlling a hydraulic actuator, wherein the hydraulic actuator includes a linear double-acting output member, and at least three working chambers in fluid connection with the output member, the working chambers having respective effective areas with a non-binary relationship; wherein the method includes selectively fluidly connecting each working chamber to either a high-pressure side or a low-pressure side to provide a plurality of discrete pressurization states of the hydraulic actuator; determining at least one of the pressurization states as a prevented pressurization state; and transitioning between a plurality of allowed pressurization states among the pressurization states while preventing transition to the at least one prevented pressurization state. A hydraulic actuator and a hydraulic system are also provided.

A method of controlling a hydraulic actuator, wherein the hydraulic actuator includes a linear double-acting output member, and at least three working chambers in fluid connection with the output member, the working chambers having respective effective areas with a non-binary relationship; wherein the method includes selectively fluidly connecting each working chamber to either a high-pressure side or a low-pressure side to provide a plurality of discrete pressurization states of the hydraulic actuator; determining at least one of the pressurization states as a prevented pressurization state; and transitioning between a plurality of allowed pressurization states among the pressurization states while preventing transition to the at least one prevented pressurization state. A hydraulic actuator and a hydraulic system are also provided.

An actuator assembly which has a primary force module having a compression spring can be is compressed by a first fluid pressure-operated piston reciprocally mounted in the primary force module. There is a tandem piston module connected to the primary force module which has a second fluid-activated piston. When the spring of the primary force module is compressed, indicating that an attached valve is in the open position, the tandem module is actuated to apply a counter balancing force against the primary piston which allows the spring to expand and move the primary piston to a position which is sufficient to permit movement of the valve element of the actuated valve to indicate the valve is not stuck in an open position.

The invention relates to a pneumatic actuator. According to one embodiment, the actuator has the following: a housing having a pressure chamber; a rod inserted into the pressure chamber of the housing from the outside; a rod seal which is located around the rod and seals the pressure chamber; and a rod guide which is mounted on the housing and is designed to guide the rod along the longitudinal axis thereof. There is no piston arranged in the pressure chamber. Rather, an unsealed annular gap is present inside the pressure chamber between the rod and an inner wall of the pressure chamber, so that a gas pressure prevailing in the pressure chamber can propagate in the entire pressure chamber as far as the rod seal.

A pressurized medium assembly includes a first working chamber and a second working chamber. The first and second working chambers are adapted to together produce a load. The pressurized medium assembly includes a first control arrangement adapted to provide a fluid communication between the first working chamber and a pressure line in an on/off manner. The pressurized medium assembly further includes a second control arrangement adapted to provide a fluid communication between the second working chamber and a pressure line. The second control arrangement is adapted to proportionally regulate the pressure in the second working chamber.

In a fluid-operated drive for a field device, the drive being designed to set a control valve of the field device, a fluidically operated basic drive is provided with a basic working chamber loaded fluidically and delimited by a basic drive housing part and by a basic actuating piston guided in the basic drive housing part. At least one supplementary drive is provided with a supplementary working chamber loaded fluidically and delimited by a supplementary drive housing part. The basic drive housing part and the supplementary drive housing part are displaceable in one another in accordance with a piston and chamber arrangement so that a volume of the supplementary chamber changes in the event of a relative movement of the drive housing parts.