Tandem pump unit

A tandem pump unit comprising:

• the integral arrangement of a first hydraulic pump and a second hydraulic pump;
• said first hydraulic pump with a first pump shaft, adapted to be connected to a first actuator via a first pair of hydraulic lines;
• said second hydraulic pump with a second pump shaft, adapted to be connected to a second actuator via a second pair of hydraulic lines;
• wherein said first pump shaft and said second pump shaft respectively having adjacent ends connected together so that said first and second pump shafts are coaxially aligned and non-rotatably connected in tandem;
• at least one housing and at least one center section connected thereto so as to define a pump accommodation chamber for accommodating the first and second hydraulic pumps;
• a charge pump for replenishing pressurized hydraulic fluid to said first pair of hydraulic lines and said second pair of hydraulic lines;
• wherein one of said first and second pump shafts extends from said pump accommodation chamber to the outside to form an extension;
• and
• wherein said charge pump is driven by said extension.

A tandem pump unit comprising:

• the integral arrangement of a first hydraulic pump and a second hydraulic pump;
• said first hydraulic pump with a first pump shaft, adapted to be connected to a first actuator via a first pair of hydraulic lines;
• said second hydraulic pump with a second pump shaft, adapted to be connected to a second actuator via a second pair of hydraulic lines;
• wherein said first pump shaft and said second pump shaft respectively having adjacent ends connected together so that said first and second pump shafts are coaxially aligned and non-rotatably connected in tandem;
• a charge line disposed within said tandem pump unit and having a first end communicating with either a reservoir or a hydraulic fluid feeding mechanism and a second end adapted to communicate with the first pair of hydraulic lines and the second pair of hydraulic lines, respectively;
• a common center section having oppositely facing sides with respect to the pump shaft direction, respectively supporting said first and second hydraulic pumps via said oppositely facing sides;
• a first pump housing and a second pump housing for respectively accommodating said first hydraulic pump and said second hydraulic pump;
• said common center section forming a first pair of inlet/outlet ports and a second pair of inlet/outlet ports, said first pair of inlet/outlet ports respectively serving as connection ports for connection with said first pair of hydraulic lines, and said second pair of inlet/outlet ports respectively serving as connection ports for connection with said second pair of hydraulic lines;
• and
• said charge line having a first bore portion, a conduit and a second bore portion, first bore portion formed in a peripheral wall of either said first pump housing or said second pump housing with a first end opening to the outside of said either the first pump housing or the second pump housing so as to communicate with said either the reservoir or the hydraulic fluid feeding mechanism and a second end opening to the inside of said either the first pump housing or the second pump housing, said conduit disposed within said either the first pump housing or the second pump housing with a first end connected to the second end of said first bore portion and a second end extending to said common center section, and said second bore portion formed in the common center section with a first end connected to the second end of the conduit and a second end communicating with the first pair of inlet/outlet ports and the second pair of inlet/outlet ports, respectively.

A tandem pump unit comprising:

• the integral arrangement of a first hydraulic pump and a second hydraulic pump;
• said first hydraulic pump with a first pump shaft, adapted to be connected to a first actuator via a first pair of hydraulic lines;
• said second hydraulic pump with a second pump shaft, adapted to be connected to a second actuator via a second pair of hydraulic lines;
• wherein said first pump shaft and said second pump shaft respectively having adjacent ends connected together so that said first and second pump shafts are coaxially aligned and non-rotatably connected in tandem;
• a charge line disposed within said tandem pump unit and having a first end communicating with either a reservoir or a hydraulic fluid feeding mechanism and a second end adapted to communicate with the first pair of hydraulic lines and the second pair of hydraulic lines, respectively;
• a common pump housing for accommodating the first and second hydraulic pumps;
• a first center section and a second center section for respectively supporting said first hydraulic pump and said second hydraulic pump;
• said common pump housing having a first opening and a second opening respectively formed at opposed ends of said pump housing with respect to the pump shaft direction, said first and second openings allowing said first and second hydraulic pumps to pass therethrough;
• said first and second center sections being respectively connected to said common pump housing so as to seal said first and second openings in a liquid tight manner;
• said first and second center sections respectively forming a first pair of inlet/outlet ports and a second pair of inlet/outlet ports serving as connection ports for connection respectively with the first pair of hydraulic lines and the second pair of hydraulic lines;
• and
• said charge line having:
• a first bore portion formed in either said first and second center sections, said first bore portion having a first end opening to the outside so as to be connected with either said reservoir or said hydraulic fluid feeding mechanism and a second end bifurcated to have two extensions, one of which communicating with one of the first and second pairs of hydraulic lines and the other opening to the inside of the housing;
• a conduit or bore portion provided in the housing to have a first end communicating with said first bore portion and a second end reaching a residual one of the first and second center sections;
• and
• a second bore portion formed in said residual one of the first and second center sections to have a first end communicating with said conduit or bore portion and second end communicating with a residual one of the first and second pairs of hydraulic lines.

A tandem pump unit comprising:

• the integral arrangement of a first hydraulic pump and a second hydraulic pump;
• said first hydraulic pump with a first pump shaft, adapted to be connected to a first actuator via a first pair of hydraulic lines;
• said second hydraulic pump with a second pump shaft, adapted to be connected to a second actuator via a second pair of hydraulic lines;
• wherein said first pump shaft and said second pump shaft respectively having adjacent ends connected together so that said first and second pump shafts are coaxially aligned and non-rotatably connected in tandem;
• a center section supporting said first hydraulic pump and said second hydraulic pump;
• a housing accommodating said first hydraulic pump and said second hydraulic pump;
• wherein said first hydraulic pump, said second hydraulic pump, said center section and said housing are integrally connected together to constitute a single unit;
• and
• a reservoir tank supportedly connected to said single unit for storing hydraulic fluid to be replenished to said first pair of hydraulic lines and said second pair of hydraulic lines.

A tandem pump unit comprising:

• a first hydraulic pump and a second hydraulic pump respectively having a first pump shaft and a second pump shaft that are coaxially aligned and non-rotatably connected in tandem;
• a center section supporting said first hydraulic pump and said second hydraulic pump;
• a housing accommodating said first hydraulic pump and said second hydraulic pump, said housing adapted to be used as a hydraulic fluid tank;
• a hydraulic fluid circulation mechanism for taking the hydraulic fluid from the hydraulic tank, and again returning the same to said hydraulic tank;
• and
• said hydraulic fluid circulation mechanism designed to cool the hydraulic fluid while circulating the same.