Hydraulic control system

Claim 2

An improvement in a fluid control system comprising: a housing having a first bore, a control spool slidable in said first bOre, said control spool having lands and intermediate grooves, said housing having a plurality of first passages intersecting said first bore for selective cooperation with said lands and grooves of said control spool, said control spool being movable between hoisting, neutral and lowering positions, said housing having inlet and outlet fluid ports, said control spool so constructed and arranged as to alternately connect two of said first passages to respective ones of said inlet and outlet ports upon movement of said control spool to hoisting and lowering positions said housing having a second bore, a second spool slidable in said second bore, said second spool having lands and intermediate grooves, said housing having a plurality of second passages intersecting said second bore for selective cooperation with said lands and grooves on said second spool, said housing having a first cylinder port connected to one of said second passages and a second cylinder port connected to another of said second passages, two of said first passages being respectively connected to two of said second passages, a spring normally maintaining said second spool toward one end of said second bore whereby lands of said second spool block the fluid flow in said second passages thereby blocking flow from said cylinder ports, pressure responsive means adapted to provide movement of said second spool against said spring whereby said second passages are opened so that fluid can flow into and out from respective cylinder ports, said pressure responsive means comprising a fluid passage from said inlet port to an end of said second bore to transmit fluid pressure thereto upon movement of said control spool to hoisting and lowering positions, and valve means in at least one of said lands on said second spool for allowing flow from one of said first passages to one of said second passages and for blocking flow from said one of said second passages to said one of said first passages when said spring is normally maintaining said second spool toward said one end of said second bore.

Claim 3

The system of claim 1 wherein said valve means comprises: a plurality of substantially axial passages through one of said lands on said second spool, a first valve plate member slidably mounted in one of said grooves of said second spool and positioned on the cylinder port side of said one of said lands, said valve plate member adapted to slide in said one of said grooves toward said land and block said plurality of passages through said one of said lands in response to fluid flow from said cylinder port, said valve plate member further adapted to slide away from said land to open said plurality of passages in response to fluid flow through said second passages into said cylinder port.

Claim 4

The system of claim 2 further comprising: a plurality of substantially axial passages through a second of said lands on said second spool, a second valve plate member slidably mounted on a second of said grooves of said second spool and positioned on the cylinder port side of said second of said lands, said valve plate member adapted to slide on said second of said grooves toward said land and block said plurality of passages through said second of said lands in response to fluid flow from said cylinder port, said valve plate member further adapted to slide away from said second of said lands to open said plurality of said passages in response to fluid flow through said second passages into said cylinder port.

Claim 5

An improvement in a fluid control system comprising: a housing having a first bore, a control spool slidable in said first bore, said control spool having lands and intermediate grooves, said housing having a plurality of first passages intersecting said first bore for selective cooperation with said lands and grooves of said control spool, said control spool being movable between hoisting, neutral, and lowering positions, said housing having inlet and outlet fluid ports, said contRol spool so constructed and arranged as to alternately connect two of said first passages to respective ones of said inlet and outlet ports upon movement of said control spool to hoisting and lowering positions, said housing having a second bore, a second spool slidable in said second bore, said second spool having lands and intermediate grooves, said housing having a plurality of second passages intersecting said second bore for selective cooperation with said lands and grooves on said second spool, said housing having a first cylinder port connected to one of said second passages and a second cylinder port connected to another of said second passages, two of said first passages being respectively connected to two of said second passages, a spring normally naintaining said second spool toward one end of said second bore whereby lands of said second spool block the fluid flow in said second passages thereby blocking flow from said cylinder ports, pressure responsive means adapted to provide movement of said second spool against said spring whereby said second passages are opened so that fluid can flow into and out from respective cylinder ports, said pressure responsive means comprising a fluid passage from said inlet port to an end of said second bore to transmit fluid pressure thereto upon movement of said control spool to hoisting and lowering positions, and means on said housing including a removable member for gaining access to said second bore from the outside of said housing to remove and interchange said second spool, said second spool further having at least two of a. first means responsive to fluid overpressure in said first cylinder port for moving said second spool away from said one end of said second bore against said spring to relieve said fluid overpressure in said first cylinder port, b. second means responsive to fluid overpressure in said second cylinder port for moving said second spool away from said one end of said second bore against said spring to relieve said fluid overpressure in said second cylinder port, and c. valve means in at least one of said lands on said second spool for allowing flow through one of said second passages into one of said cylinder ports from one of said first passages and for stopping flow from said one of said cylinder ports to said one of said first passages when said second spool is being normally maintained toward said one end of said second bore by said spring.

Claim 6

An improvement in a fluid control system comprising: a housing having a first bore, a control spool slidable in said first bore, said control spool having lands and intermediate grooves, said housing having a plurality of first passages intersecting said first bore for selective cooperation with said lands and grooves of said control spool, said control spool being movable between hoisting, neutral, and lowering positions, said housing having inlet and outlet fluid ports, said contRol spool so constructed and arranged as to alternately connect two of said first passages to respective ones of said inlet and outlet ports upon movement of said control spool to hoisting and lowering positions, said housing having a second bore, a second spool slidable in said second bore, said second spool having lands and intermediate grooves, said housing having a plurality of second passages intersecting said second bore for selective cooperation with said lands and grooves on said second spool, said housing having a first cylinder port connected to one of said second passages and a second cylinder port connected to another of said second passages, two of said first passages being respectively connected to two of said second passages, a spring normally naintaining said second spool toward one end of said second bore whereby lands of said second spool block the fluid flow in said second passages thereby blocking flow from said cylinder ports, pressure responsive means adapted to provide movement of said second spool against said spring whereby said second passages are opened so that fluid can flow into and out from respective cylinder ports, said pressure responsive means comprising a fluid passage from said inlet port to an end of said second bore to transmit fluid pressure thereto upon movement of said control spool to hoisting and lowering positions, and means on said housing including a removable member for gaining access to said second bore from the outside of said housing to remove and interchange said second spool, said second spool further having at least two of a. first means responsive to fluid overpressure in said first cylinder port for moving said second spool away from said one end of said second bore against said spring to relieve said fluid overpressure in said first cylinder port, b. second means responsive to fluid overpressure in said second cylinder port for moving said second spool away from said one end of said second bore against said spring to relieve said fluid overpressure in said second cylinder port, and c. valve means in at least one of said lands on said second spool for allowing flow through one of said second passages into one of said cylinder ports from one of said first passages and for stopping flow from said one of said cylinder ports to said one of said first passages when said second spool is being normally maintained toward said one end of said second bore by said spring.

Claim 7

An improvement in a fluid control system comprising: a housing having a first bore, a control spool slidable in said first bore said control spool having lands and intermediate grooves, said housing having a plurality of first passages intersecting said first bore for selective cooperation with said lands and grooves of said control spool, said central spool being movable between hoisting, neutral, and lowering positions, said housing having said housing and outlet fluid ports, said control spool so constructed and arranged as to alternately connect two of said first passages to respective ones of said inlet and outlet ports upon movement of said control spool to hoisting and lowering positions said housing having a second bore, a second spool slidable in said second bore, said second spool having lands and intermediate grooves, said housing having a plurality of second passages intersecting said second bore for selective cooperation with said lands and grooves on said second spool, said housing having a first cylinder port connected to one of said second passages and a second cylinder port connected to another of said second passages, two of said first passages being respectively connected to two of said second passages, a spring normally maintaining said second spool in a first position adjacent to one end of said second bore whereby lands of said second spool block the fluid flow in said second passages thereby blocking flow from said cylinder ports, pressure responsive means for moving sAid second spool against said sprinig and away from said one end of said second bore to a second position wherein said second passages are open so that fluid can flow into and out from said respective cylinder ports, said pressure responsive means comprising a fluid passage from said inlet port to said one end of said second bore to transmit fluid pressure to said one end of said second bore upon movement of said control spool to hoisting and lowering positions, said second spool being operable to move only between said first and second positions, said second spool having a longitudinal bore, said longitudinal bore having one end opening toward said one end of said second bore and the other end terminating in said second spool, a first plunger slidably mounted in said longitudinal bore, a first port in said second spool connecting one of said cylinder ports to said longitudinal bore whereby fluid overpressure in said cylinder port is transmitted to said longitudinal bore to exert force on one end of said plunger and said second spool, thereby causing said second spool to move axially against said spring to momentarily open passage from said cylinder port to one of said first and second connected passages to relieve overpressure in said cylinder port, and a second plunger slidably mounted in the same longitudinal bore, a second port in said second spool connecting a location in said longitudinal bore between said first and second plungers to the second of said cylinder ports whereby fluid overpressure in said second cylinder port is transmitted to said longitudinal bore to exert a force on said second plunger and said second spool, thereby causing said second spool to move axially against said spring to momentarily open passage from said second cylinder port to the other of said first and second connected passages to relieve overpressure in said second cylinder port.

Claim 8

An improvement in a fluid control system comprising: a housing having a first bore, a control spool slidable in said first bore said control spool having lands and intermediate grooves, said housing having a plurality of first passages intersecting said first bore for selective cooperation with said lands and grooves of said control spool, said central spool being movable between hoisting, neutral, and lowering positions, said housing having said housing and outlet fluid ports, said control spool so constructed and arranged as to alternately connect two of said first passages to respective ones of said inlet and outlet ports upon movement of said control spool to hoisting and lowering positions said housing having a second bore, a second spool slidable in said second bore, said second spool having lands and intermediate grooves, said housing having a plurality of second passages intersecting said second bore for selective cooperation with said lands and grooves on said second spool, said housing having a first cylinder port connected to one of said second passages and a second cylinder port connected to another of said second passages, two of said first passages being respectively connected to two of said second passages, a spring normally maintaining said second spool in a first position adjacent to one end of said second bore whereby lands of said second spool block the fluid flow in said second passages thereby blocking flow from said cylinder ports, pressure responsive means for moving sAid second spool against said sprinig and away from said one end of said second bore to a second position wherein said second passages are open so that fluid can flow into and out from said respective cylinder ports, said pressure responsive means comprising a fluid passage from said inlet port to said one end of said second bore to transmit fluid pressure to said one end of said second bore upon movement of said control spool to hoisting and lowering positions, said second spool being operable to move only between said first and second positions, said second spool having a longitudinal bore, said longitudinal bore having one end opening toward said one end of said second bore and the other end terminating in said second spool, a first plunger slidably mounted in said longitudinal bore, a first port in said second spool connecting one of said cylinder ports to said longitudinal bore whereby fluid overpressure in said cylinder port is transmitted to said longitudinal bore to exert force on one end of said plunger and said second spool, thereby causing said second spool to move axially against said spring to momentarily open passage from said cylinder port to one of said first and second connected passages to relieve overpressure in said cylinder port, and a second plunger slidably mounted in the same longitudinal bore, a second port in said second spool connecting a location in said longitudinal bore between said first and second plungers to the second of said cylinder ports whereby fluid overpressure in said second cylinder port is transmitted to said longitudinal bore to exert a force on said second plunger and said second spool, thereby causing said second spool to move axially against said spring to momentarily open passage from said second cylinder port to the other of said first and second connected passages to relieve overpressure in said second cylinder port.

Claim 9

An improvement in a fluid control system comprising: a housing having a first bore, a control spool slidable in said first bore, said control spool having lands and intermediate grooves, said housing having a plurality of first passages intersecting said first bore for selective cooperation with said lands and grooves of said control spool, said control spool being movable between hoisting, neutral, and lowering positions, said housing having inlet and outlet fluid ports, said control spool so constructed and arranged as to alternately connect two of said first passages to respective ones of said inlet and outlet ports upon movement of said control spool to hoisting and lowering positions, said housing having a second bore, a second spool slidable in said second bore, said second spool having lands and intermediate grooves, said housing having a plurality of second passages intersecting said second bore for selective cooperation with said lands and grooves on said second spool, said housing having a first cylinder port connected to one of said second passages, and a second cylinder port in said housing connected to another of said second passages, two of said first passages being respectively connected to two of said second passages, a spring normally maintaining said second spool in a first position adjacent to one end of said second bore, the lands of said second spool cooperating with said second bore and said second passages when said second spool is in said first position so as to block the fluid floow in one of said second passages to thereby block the fluid flow from one of said cylinder ports and so as to open one of said second passages to fluid flow to thereby place the other of said cylinder ports in open fluid connection with one of said first passages, said housing having a third bore placed substantially coaxially with said second bore, a piston in said third bore, said piston in abutting engagement with said second opposite said spring, pressure responsive means for moving said second spool against said spring and away from said one end of saiD second bore to a second position wherein said second passages are opened so that fluid can flow into and out from the cylinder ports, said pressure responsive means comprising a fluid passage from said inlet port to an end of said third bore to transmit fluid pressure to said end of said third bore upon movement of said control spool to hoisting and lowering positions thereby causing said piston to move toward said second spool and causing said second spool to move to said second position, said second spool being operable to move only between said first and second positions.

Claim 10

An improvement in a fluid control system comprising: a housing having a first bore, a control spool slidable in said first bore, said control spool having lands and intermediate grooves, said housing having a plurality of first passages intersecting said first bore for selective cooperation with said lands and grooves of said control spool, said control spool being movable between hoisting, neutral, and lowering positions, said housing having inlet and outlet fluid ports, said control spool so constructed and arranged as to alternately connect two of said first passages to respective ones of said inlet and outlet ports upon movement of said control spool to hoisting and lowering positions, said housing having a second bore, a second spool slidable in said second bore, said second spool having lands and intermediate grooves, said housing having a plurality of second passages intersecting said second bore for selective cooperation with said lands and grooves on said second spool, said housing having a first cylinder port connected to one of said second passages, and a second cylinder port in said housing connected to another of said second passages, two of said first passages being respectively connected to two of said second passages, a spring normally maintaining said second spool in a first position adjacent to one end of said second bore, the lands of said second spool cooperating with said second bore and said second passages when said second spool is in said first position so as to block the fluid floow in one of said second passages to thereby block the fluid flow from one of said cylinder ports and so as to open one of said second passages to fluid flow to thereby place the other of said cylinder ports in open fluid connection with one of said first passages, said housing having a third bore placed substantially coaxially with said second bore, a piston in said third bore, said piston in abutting engagement with said second opposite said spring, pressure responsive means for moving said second spool against said spring and away from said one end of saiD second bore to a second position wherein said second passages are opened so that fluid can flow into and out from the cylinder ports, said pressure responsive means comprising a fluid passage from said inlet port to an end of said third bore to transmit fluid pressure to said end of said third bore upon movement of said control spool to hoisting and lowering positions thereby causing said piston to move toward said second spool and causing said second spool to move to said second position, said second spool being operable to move only between said first and second positions.

Claim 11

In the system of claim 6 the improvement further comprising: said second spool having a longitudinal bore having one end open toward said one end of said second bore and the other end terminating in said second spool, a plunger slidably mounted in said longitudinal bore, a first port in said second spool connecting the other of said cylinder ports to said longitudinal bore whereby fluid pressure in said one of said cylinder ports is transmitted to said longitudinal bore to exert force on one end of said plunger and said second spool, thereby causing said second spool to move axially against said spring to momentarily open passage from said one of said cylinder ports to one of said first and second connected passages to relieve overpressure in said second cylinder port.