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Southern Alberta Canada | Load sensing hydraulics run a standby pressure of usually around 200 to 500psi, when a load is applied it will always maintain that pressure over the highest demand pressure to max set pressure. Case tractors from the 90 series on use load sensing hydraulics. John Deere ran closed center since the '60s, they switched over to load sense with the 00 series four wheel drives.
The load sense port on your tractor needs to be tied into a load sense style valve on your implement, it needs the ability to pressurize the load sense line when operating then dump it to tank when idle in order to work with the load sensing valves on the tractor.
Power beyond actually only applies to open center systems, it's basically a flow diverter built into the upstream valve. What happens is when you operate the upstream valve pump oil is diverted to that section and returned to tank bypassing downstream valves thus making them inoperable until the upstream valve is returned to nuetral. For closed center and load sensing systems power beyond is just a tee in the pump line, the valve with the least resriction gets oil first up to it's flow setting then oil is shared with the next lowest restriction and so on. There are valves that will attempt to share oil as equal as possible between sections and demand.
Case drains are bleed off ports on the motor cases that prevent pressure buildup within the case and blowing shaft seals. They are typically used where return oil pressure can build due to restrictions caused by filters, long lines, components tyed in downstream such as motors in series and such. | |
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hydraulic theory - explain all the power beyond connections to me
