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Filter arrangement for single-acting telescopic hydraulic cylinders

  • US 5,535,588 A
  • Filed: 05/06/1994
  • Issued: 07/16/1996
  • Est. Priority Date: 05/06/1994
  • Status: Expired due to Fees
First Claim
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1. A spin-on assembly useable for connecting a hydraulic cylinder for a dump truck bed to a hydraulic pump the assembly comprising:

  • a single hydraulic line connecting the hydraulic cylinder to the hydraulic pump;

    a base with a first port and a second port,the ports being connected by a chamber and connecting the single hydraulic line to one chamber;

    an externally threaded outlet tube projecting from the chamber;

    a spin-on housing having an end plate with a threaded central opening for threadably mounting the housing on the threaded outlet tube and inlet openings therethrough;

    an annular filter element disposed in the housing, the annular filter element defining a central space into which the hydraulic fluid flows, the central space receiving the threaded outlet tube;

    a first one-way check valve axially disposed in the threaded outlet tube in series with the filter element and in communication with both the central space of the annular filter element and the chamber in the base, the first one-way check valve being oriented and biased closed by a first spring exerting a first spring force to block fluid flow from the first port to the central space and to allow fluid flow at a first selected pressure exerting a force greater than the first force from the central space to the first port, anda second one-way check valve disposed in parallel with the filter element and positioned in the chamber between the first one-way check valve and the second port, the second one-way check valve being oriented and biased closed by a second spring exerting a second force to block fluid flow from the second port to the first port and to allow flow at a second selected pressure exerting a second force greater than the second spring force from the first port to the second port, the second selected pressure being substantially greater than the first selected pressure level whereby fluid pressure applied to the first port from the hydraulic pump applies a back pressure to keep the first one-way check valve closed while opening the second one-way check valve, and whereby fluid flow from the hydraulic cylinder into the second port at a pressure greater than the first pressure flows through the filter element into the central space, out through the first one-way check valve, into the chamber and out of the first port.

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