Apparatus for cleaning a hydraulic fluid

An apparatus for cleaning a hydraulic fluid of a hydraulic system, said apparatus comprising:

• a fluid container adapted to receive and contain a quantity of the hydraulic fluid,
• fluid cleaning means for removing contaminants from the hydraulic fluid,
• a first conduit connecting said fluid container to said fluid cleaning means,
• a second conduit connecting said fluid cleaning means to said fluid container,
• pump means interposed in said first conduit or in said second conduit and adapted to convey the hydraulic fluid in sequence from the fluid container, through the first conduit, through the fluid cleaning means, through the second conduit and into the fluid container,
• an outlet line connected to said second conduit and having an outlet end adapted to be removably connected to the hydraulic system,
• an inlet line connected to said first conduit and having an inlet end adapted to be removably connected to the hydraulic system,
• a high pressure pump interposed in said outlet line and adapted to pump the hydraulic fluid from said second conduit, through said outlet line, through said outlet end, and into the hydraulic system, and
• a pressure maintaining valve interposed in said inlet line and adapted to selectively restrict a flow of the hydraulic fluid through said inlet line to maintain a pressure in the hydraulic system.

A method of cleaning a hydraulic fluid of a hydraulic system using an apparatus including a fluid container, a contaminant removal device, and a circulation pump connected in series with said fluid container and said contaminant removal device to form a circulation loop, a high pressure pump in an outlet line branching off from said circulation loop on an upstream side of said fluid container, and a pressure regulating valve in an inlet line branching off from said circulation loop on a downstream side of said fluid container, said method comprising the following steps:

• (a) connecting said inlet line to a first port of said hydraulic system, and connecting said outlet line to a second port of said hydraulic system;
• (b) after said step (a) and while said inlet line and said outlet line are respectively connected to said first and second ports of said hydraulic system, operating said circulation pump to circulate said hydraulic fluid around said circulation loop from said fluid container through said contaminant removal device and back into said fluid container;
• and
• (c) during said step (b), operating said high pressure pump to pressurize said hydraulic fluid to a hydraulic system pressure and pump said hydraulic fluid through said outlet line, into said second port, into and through said hydraulic system, out of said second port and through said inlet line at said hydraulic system pressure, wherein said pressure regulating valve maintains said hydraulic system pressure at a pressure level higher than a cleaning apparatus pressure present within said circulation loop.