Abstract: A hydraulic cylinder has an internal shaft that rotates in response to extension or contraction of an output rod. A magnet is affixed to the shaft, the position of which is detected by a sensor internal to the hydraulic cylinder for determining the position of the output rod.

Abstract: A hydraulic device that includes a case, and a substantially hollow rod slidably extending from the case. The rod has a ram on a first end thereof that caps the rod to form a first hydraulic piston. The rod has a second hydraulic piston on a second end thereof, inside the case. The first and second pistons are at least partially radially coextensive, and a pressure barrier inhibits high pressure on the first piston inside the hollow rod from reaching a side of the second piston that faces the first piston.

Abstract: A hydraulic swivel has a case defining a substantially cylindrical interior and a first access port defined in a side thereof, the first access port providing a path for fluid communication between an interior and an exterior of the case. A spool occupies the interior of the case, the spool and the case together defining a first circumferential channel such that the access port is in fluid communication with the channel regardless of the rotational relationship between the case and the spool, and wherein the spool defines a first interior passageway, the first interior passageway having a port connecting to the first circumferential channel. An actuator occupies at least a portion of the first interior channel selectively blocking and enabling fluid communication between the first circumferential channel and the first interior passageway and therefore selectively blocking and enabling fluid communication between the access port and the first interior passageway.