Circuit for the control of a winch by fluid under pressure including an unwinding position

Claim 2

A hydraulic circuit for the control of a winch by fluid under pressure, including an unwinding position, comprising: a fluid motor having an inlet chamber and an exhaust chamber for the fluid, a source of fluid under pressure, a fluid tank, a feed-pipe connecting the source of fluid to the inlet chamber, a delivery pipe having an upstream end connected to the exhaust chamber and a downstream end communicating with the fluid tank, a first calibrated discharge valve which is arranged in the delivery pipe, a connecting tie-pipe which is connected on one end to the delivery pipe downstream of the first calibrated discharge valve with respect to the motor and is connected on an opposite end to the feed pipe, a flow constriction member for adjustment of the flow of fluid in the tie-pipe, and a second calibrated discharge valve arranged in the delivery pipe downstream of the connection of the tie-pipe to the delivery pipe.

Claim 3

A circuit as in claim 1, including: a by-pass pipe by-passing the first and second calibrated valves, which by-pass pipe has one end connected to the delivery pipe at a location between the motor and the first calibrated valve and which has its other end connected to the delivery pipe at a location downstream of the second calibrated valve with respect to the first calibrated valve, a first regulator valve having at least two positions, which is mounted in the by-pass pipe and which in its first position blocks the by-pass pipe and in its second position ensures the continuity of the said by-pass pipe, a second regulator valve having at least two positions, which is arranged in the connecting tie-pipe and which in its first position ensures the continuity of the connecting tie-pipe and in its second position blocks the said tie-pipe, and a control means for concurrently maintaining the first and second regulator valves in either their first positions or in their second positions.

Claim 4

A circuit as in claim 2, said control means including: a source of piloting fluid, a first jack and a first return member which are coupled to the movable member of the first regulator valve, the first jack being connected by a first piLoting pipe to the source of piloting fluid and having an effect upon the said movable member, which is opposed to that of the first return member, this latter effect returning the said movable member towards the second position of the first regulator valve, a second jack and a second return member which are coupled to the movable member of the second regulator valve, the second jack being connected by a second piloting pipe to the source of piloting fluid and having an effect upon the said movable member, which is opposed to that of the second return member, this latter effect returning the said movable member towards the second position of the second regulator valve, third regulator valve means having first and second selective positions for connecting said first and second piloting pipes to said source of piloting fluid when in its first position and for connecting said first and second piloting pipes to vent to said fluid tank when in said second position.

Claim 5

A circuit as in claim 3, including a third calibrated valve arranged in the delivery pipe downstream of the second calibrated valve and of the connection to the by-pass pipe, which is itself located downstream of the said second calibrated valve with respect to the first calibrated valve, the source of piloting fluid comprises the portion of the delivery pipe lying between the second calibrated valve and said third calibrated valve.