High pressure implement hydraulic circuit

Claim 2

In combination with a fluid motor control mechanism having an inlet passage connected with a fluid pressure source and at least one controlled passage through which motor exhaust in communication with said controlled passage can be vented to reservoir: a. a pilot controllable exhaust valve mechanism biased to block discharge flow of exhaust fluid to reservoir from said controlled passage, b. a pilot control means associated wiTh said controllable exhaust valve mechanism comprising: i. a first pilot instrumentality which is operable to effect opening of the exhaust valve mechanism whenever pressure of the exhaust fluid in said controlled passage rises to a first predetermined value, and ii. a second pilot instrumentally which is also arranged to effect opening of the exhaust valve mechanism and having communication with the fluid pressure source and being operable to effect opening of said exhaust valve mechanism in consequence of a rise in pressure on an inlet side of said fluid motor which has its motor exhaust in communication with said controlled passage.

Claim 3

The combination of claim 1 wherein the first pilot instrumentality includes a spring loaded poppet operable to unseal and allow the exhaust valve mechanism to open at the first predetermined value.

Claim 4

The combination of claim 1 wherein the second pilot instrumentality includes a control valve having fluid communication with the fluid pressure source and connected to said controllable exhaust valve mechanism and operable to cause said controllable exhaust valve mechanism to open at a different pressure than the first predetermined pressure.

Claim 5

The combination as defined in claim 1 wherein a check valve in connected between the controlled passage and the inlet passage connected to the fluid pressure source.

Claim 6

The combination defined in claim 4 wherein the check valve between the controlled passage and the inlet passage includes a third pilot instrumentality so it is pilot controlled.

Claim 7

The combination defined in claim 1 wherein the motor control mechanism includes at least two controlled passages and a separate check valve between the inlet passage and each controlled passage, each of said check valves including a third pilot instrumentality whereby they can be pilot operated, and each controlled passage having a separate pilot controllable exhaust valve mechanism biased to block discharge flow of exhaust fluid from its associated controlled passage to reservoir with each of said pilot controllable exhaust valve mechanisms having a first and second pilot instrumentality.

Claim 8

The combination defined in claim 6 wherein the pilot control means includes a control valve having communication with the source of pressurized fluid and separate connections with all of the pilot instrumentalities associated with the check valves and the pilot controllable exhaust valve mechanisms with opposite sides of a fluid motor connected to the two separate controllable passages and a spool means in said control valve operable in one position to control pressurization of the third pilot instrumentality of a check valve in one of said controlled passages to open said check valve and to simultaneously open said pilot controllable exhaust mechanism in said other controlled passage at a pressure different from the first predetermined pressure whereby the motor exhaust entering said other controlled passage will be vented to reservoir at a different pressure than the first predetermined paressure and also operable in another position to operate to control the pressurization of the other third pilot instrumentality of the other check valve in the other of said controlled passages to open said check valve and to simultaneously open said other pilot controllable exhaust mechanism in said controlled passage, whereby motor exhaust entering either of said passages will be vented to reservoir at a different pressure than predetermined pressure. 8.The combination defined in claim 7 wherein the control valve includes a spool with manual positioniong means connected thereto, said spool having a plurality of lands to control pressurization of the connections in various positions, in one position of said spool one of said pilot controllable exhaust valve mechanisms being conditioned to open at a different pressure than the first predetermined pressure to the exclusion of the other of said pilot controllable exhaust valve mechanisms and in another poSition of said spool both of said pilot controllable exhaust valve mechanisms being conditioned to open at a different pressure than said first predetermined pressure.