Abstract: A system for controlling the rotational position of a solar collector trough includes a hydraulic cylinder having an output end and a linkage assembly. The linkage assembly includes at least one linkage member and a pair of pivot arms attached to the at least one linkage member. The pair of pivot arms is defined by a first pivot arm and a second pivot arm, each arm being pivotally attached to the at least one linkage member and the trough. The first and second pivot arms form respective parallel horizontal first and second pivot axes enabling the trough to be entirely movable over an angular range of motion extending over 180 degrees based totally on the linear movement of the output end of the hydraulic cylinder and in which an actuator control circuit controls the relative displacement of the cylinder output end.

Abstract: A system for controlling the rotational position of a solar collector trough includes a hydraulic cylinder having an output end and a linkage assembly. The linkage assembly includes at least one linkage member and a pair of pivot arms attached to the at least one linkage member. The pair of pivot arms is defined by a first pivot arm and a second pivot arm, each arm being pivotally attached to the at least one linkage member and the trough. The first and second pivot arms form respective parallel horizontal first and second pivot axes enabling the trough to be entirely movable over an angular range of motion extending over 180 degrees based totally on the linear movement of the output end of the hydraulic cylinder and in which an actuator control circuit controls the relative displacement of the cylinder output end.

Abstract: An all-electric transport refrigeration system receives its compressor drive motor power and all other electrical power from at least one on-board fuel cell. The fuel cell is able to power all of the refrigeration system electrical components. In one example a single fuel cell is used. Another example includes multiple fuel cells.

Abstract: In its unstressed state, a suction valve is spaced from its valve seat such that the suction valve must be deformed against its inherent spring force in order to achieve seating. The spring force due to deformation provides an opening bias to the suction valve such that it opens earlier in the suction stroke and offsets the effects of adhesion due to the presence of oil between the seating surface and the valve.

Abstract: A compressor piston has protrusions which extend upwardly into discharge ports to minimize clearance at the end of the compression stroke. The protrusions fit into circumferentially isolated discharge ports, and each of the ports are associated with reed valves. Preferably a cutout portion is formed into the piston head to allow clearance for movement of the suction valve. The suction valve is positioned on an inner face of a valve plate and the discharge reed valves are positioned on an outer face. The protrusions are preferably frustro-conical.

Abstract: An all-electric transport refrigeration system receives its compressor drive motor power and all other electrical power from at least one on-board fuel cell. The fuel cell is able to power all of the refrigeration system electrical components. In one example a single fuel cell is used. Another example includes multiple fuel cells.

Abstract: The seat of a suction valve of a reciprocating compressor is modified to limit the radial extent and thereby the area in which an annular oil film can be established between the valve and the valve seat. The preferred radial extent of the seating surface is 0.014 to 0.018 inches and the preferred ratio of the area of the suction valve seat to the passage therethrough is in the range of 13% to 25%.

Abstract: A compressor piston has protrusions which extend upwardly into discharge ports to minimize clearance at the end of the compression stroke. The protrusions fit into circumferentially isolated discharge ports, and each of the ports are associated with reed valves. Preferably a cutout portion is formed into the piston head to allow clearance for movement of the suction valve. The suction valve is positioned on an inner face of a valve plate and the discharge reed valves are positioned on an outer face. The protrusions are preferably frustro-conical.

Abstract: The seat of a suction valve of a reciprocating compressor is modified to limit the area in which an annular oil film can be established between the valve and the valve seat. The seat is configured to limit the oil film from 3% to 33% of the total inlet port opening. In a modified embodiment gas at discharge pressure exerts an opening bias to the suction valve at the end of the discharge stroke.

Abstract: At start up, at least one bank of cylinders of a compressor is allowed to compress gas and deliver the compressed gas to the system while at least the majority of the other banks are subject to hot gas bypass. The entire compressor is subject to suction modulation such that the amount of gas that can be compressed and delivered by all of the operating banks can be controlled and thereby the compressor power demand is controlled.

Abstract: In a positive displacement compressor having a plurality of banks, operation can be multi-staged or single staged. Single stage operation can be of a single bank or plural banks in parallel. Switchover between modes of operation is under the control of a microprocessor responsive to sensed inputs. During pulldown under ambient or condenser entering air temperatures of 100.degree. F., or more, suction modulation is used to limit the suction pressure thereby permitting a switchover to two-stage operation and the use of an economizer.

Abstract: In a positive displacement compressor having a plurality of banks, operation can be multi-staged or single staged. Single stage operation can be of a single bank or plural banks in parallel. Switch-over between modes of operation is under the control of a microprocessor responsive to sensed inputs.

Abstract: In a compressor having a plurality of banks of cylinders, smaller steps of unloading are achieved by unloading a single cylinder in a bank. When only one cylinder is to be unloaded, gas bypass is used in order to maintain a closer balance of forces in the bank. When the entire bank is unloaded, it is preferably done via the suction cutoff method.