Abstract: A proportional control fluid actuator that is used as a positioning device in applications such as a hydraulic directional control valve. The activating device has a cylinder body attachable to a valve body and has a bore carrying a piston that is coaxially secured to an end of a valve spool. The device is provided with spaced openings in the cylinder body that communicate with the bore therein to introduce fluid to act on opposite sides of the piston. Factory pre-compressed spring means are provided for normally urging the piston and spool to a center position. Since the areas of the fluid pressure applied on both sides of the piston are different (due to a spool on one side of the piston), two pre-compressed springs are used to compensate the area difference to achieve a proportional movement of the spool.

Abstract: A proportional control fluid actuator that is used as a positioning device in applications such as a hydraulic directional control valve. The activating device has a cylinder body attachable to a valve body and has a bore carrying a piston that is coaxially secured to an end of a valve spool. The device is provided with spaced openings in the cylinder body that communicate with the bore therein to introduce fluid to act on opposite sides of the piston. Factory pre-compressed spring means are provided for normally urging the piston and spool to a center position. Since the areas of the fluid pressure applied on both sides of the piston are different (due to a spool on one side of the piston), two pre-compressed springs are used to compensate the area difference to achieve a proportional movement of the spool.

Abstract: A proportional control pneumatic cylinder as an air actuator device for a hydraulic pump valve having a valve spool moving in a bore in a valve housing. The device having an actuator housing attachable to the valve housing and having a bore carrying a piston coaxially secured to an end of the valve spool. The device provided with spaced openings in the actuator housing which communicate with the bore therein to introduce air to act on opposite sides of the piston, and factory pretensioned biasing means for normally urging the piston and spool to a center closed position. Surface areas on opposite sides of the piston are approximately equal so that piston movement is approximately proportional to movement of an actuating lever of an air supplying pneumatic control valve over the majority of the range of travel of the actuating lever for both raised and lowered positions.

Abstract: A three position fluid powered actuator having a piston reciprocally positioned within a cylindrical chamber in a body. The piston has a socket in communication with an axial opening through the piston. A piston shaft has a first end passing through the axial opening and into the socket and has a second end passing through a spring chamber in the body. A compression spring surrounds the piston shaft in the spring chamber. A pair of fluid passageways extend into the cylindrical chamber, whereby fluid pressure in a first passageway will move the piston in a first direction and fluid pressure in a second passageway will move the piston in a second direction.

Abstract: A planting hole burning apparatus and method of forming a row of spaced planting holes through a plastic film positioned atop a seed growing bed. The apparatus includes ground engaging wheels which support a frame. A heat dispenser rotor is connected to the frame for rotation about an axis transverse to the direction of travel of the apparatus in use. The rotor is made to rotate at a speed proportional to the ground speed of the apparatus and such that a distal end of the rotor moves arcuately in very close proximity to the plastic film at the bottom of the arc. Gearing and rotor length are selected so that the arcuate speed of the distal end of the rotor during its rearward travel at the bottom portion of its swing is equal to the ground speed of the apparatus. Various means for heating one or more distal ends of the rotor for burning the planting holes through the plastic film while rotating in close proximity to the plastic film are provided.

Abstract: A pruning boom for pruning or trimming trees, bushes, shrubs and the like. A plurality of circular saw blades are rotatably mounted on a saw carrying member. Each saw blade is positioned for rotation in a spatial plane which intersects the spatial plane containing the surface of the saw carrying member located immediately behind the saw blades at an identical non-perpendicular angle. In the preferred embodiment of the present invention, one pruning boom is mounted on each side of the front-end of an agricultural vehicle to construct a machine for pruning parallel rows of citrus trees. During such pruning operations, the angular relationship between the rotating saw blades and the saw carrying member prevents newly cut branches and limbs from wedging in the space between the saw blades and the saw carrying member. The saw blades are overlapped at their peripheries with the uppermost portion of each saw blade positioned behind the lowermost portion of the adjacent saw blade above it on the saw carrying member.