US2906378A - Remote controlled oil well hoist brake - Google Patents

Description

Sept. 29, 1959 R. c. MCNEILL REMOTE CONTROLLED OIL WELL HOIST BRAKE 2 Sheets-Sheet 1 Filed Feb. 25, 1957 FIGURE I iilrll' FIGURE 4 FIGURE 3 INVENTOR= ROBERT C. McNElLL fi/I/(J Mu H'IS ATTORNEY R. C. MONEILL REMOTE CONTROLLED OIL WELL HOIST BRAKE Sept. 29, 1959 Filed Feb. 25, 1957 2 Sheets-Sheet 2 MASTER /CYLINDER V 3 l i 3 9 imnwmliwi RESERVOIR COMPENSLATING SLAVE CYLINDE E C R sU 0 s P INVENTOR ROBERT C. McNElLL 4014s era/dam HIS A TORNEY FIGURE 2 United States Patent REMOTE CONTROLLED OIL WELL HOIST BRAKE Application February 25, 1957, Serial No. 642,048

2 Claims. (Cl. 188151) This invention relates to oil well apparatus and pertains, more particularly, to a hoist brake remote control system for use with a drawworks hoist servicing unit hoist and the like.

An object of this invention is to provide a new and improved remote control system whereby an operator can control a hoist from a remote point providing him with an unobstructed view of the oil well apparatus.

Another object is to provide such a system whereby an operator can feel the action of the brake as he applies it, thereby aiding his control over the operation being undertaken.

Yet another object is to provide such a system including fail-safe features adapted to set the brake should the system fail or become unadjusted. These and other objects and advantages of this invention will be understood from the following description taken with reference to the accompanying drawings wherein:

Fig. 1 is a diagrammatic view showing the system of the present invention in use with the hoist of a mobile well-servicing unit;

Fig. 2 is a schematic diagram of the present system;

Fig. 3 is a diagrammatic view in vertical section of an air relay valve which may be used in the system;

Fig. 4 is a diagrammatic view in vertical section of a hydraulic fluid reservoir which may be used in the system.

Referring to the drawings, there is shown a mobile well-servicing unit including a truck 1 and a mast or derrick 2 which is pivotally attached to the rear end of the truck bed and is shiftable by the usual hydraulic apparatus 3 between a horizontal transport position (not shown) and an upstanding working position (Fig. l). The drawworks 4 is carried adjacent the cab end of the truck bed and embodies a suitable hoist prime mover means, a hoist drum 5 and a suitable brake, diagrammatically shown at 6, for controlling rotation of the drum 5 when under a load. The derrick is provided with the usual hoist gear including the crown block 7, the traveling block 8, and a hook or clamp 9 which, in operation, is connected to the apparatus for servicing the well 10.

Referring now to Figs. 1 and 2, in accordance with the present invention, the hoist brake 6 is operated from a control center 11 by a hydraulic system embodying a brake lever 19 which is located at the center 11 and associated apparatus which may be located in a housing '20 disposed on the truck bed. Preferably, other controls, for example, the clutch and throttle controls (not or a wellshown) for the hoist prime mover means, are also located at the control center 11. The controls may be mounted on a light portable panel or stand 12 which preferably is located near the foot of the derrick adjacent the well head so that the operator may observe the action at the well head and at the derrick mans position without looking into the sun.

More particularly, the system is a closed positive displacement system which operates above a predetermined minimum hydraulic pressure. The system, preferably, is supplied with pressure fluid from a pressurized compensating reservoir 22 provided with a pressure gage 23 and a self-sealing hydraulic fluid supply nipple 53, so that the reservoir 22 can be refilled with fluid when necessary and before minimum permissible pressure has been reached due to normal leakage from the system.

Pressure fluid is supplied from the reservoir 22 through a hydraulic line 24 including a flow restricting orifice 25 to a pair of branch lines 26 and 27 which communicate with the opposite ends of a hydraulic master cylinder 28. The branch lines 26 and 27 are provided with check valves 29, respectively, which prevent recirculation of pressure fluid back into the reservoir 22. If desired, the orifice 25 can be incorporated in the check valves.

The master cylinder 28 is located at the control center 11 and includes a piston 30 and a piston rod 31 which is pivotally connected, for example, intermediate the pivoted end and the free end of the brake lever 19, which lever is manipulated by the operator for shifting the piston 30 and applying and releasing the brake 6, as subsequently more fully described.

A pair of hydraulic lines 32 and 33 communicate be tween the opposite ends of the master cylinder 28 and a slave cylinder 34 which is arranged in the housing 20. A slave cylinder piston 35 carries a piston rod 36 which is pivotally connected to the arm 37 of a cam fixed to a brake shaft 39 which, when rotated in opposite directions, operates in a well-known manner to apply or release the brake 6. For example, in Fig. 2, rotation of the shaft 39 in a clock-wise direction viewed from the brake end of the shaft operates to apply the brake. From the foregoing, it will be seen that when the brake lever 19 is raised, hydraulic fluid is displaced in one direction in the system for shifting the piston 35 to release the brake. A downward movement of the lever 10 reverses the displacement of hydraulic fluid in the system and moves the piston 35 to apply or set the brake. Since a closed positive displacement system is provided, the force applied to the brake lever by the operator is directly mechanically affected by the force resisting application of the brake, and the operator can feel the extent of the braking action and readily control rotation of the hoist drum 5.

One embodiment of the compensating reservoir 22 is shown in Figs. 2 and 4 as comprising a cylindrical pressure vessel 40 having an air tight bellows or collapsible bag 41 disposed in its upper interior portion and connected by an air line 42 through a three-wave valve 43 to a source 44 of constant pressure. The bottom side of the bellows bears on the upper side of a slidable piston 50 which is urged upwardly by a compression spring 51 confined between the piston 50 and an annular shoulder 52. The portion of the vessel chamber beneath the piston 50 is normally filled with hydraulic fluid. The hydraulic fluid supply nipple 53 communicates through one side of the fluid chamber and the pressure gage 23 communicates through the other side.

In operation, when the reservoir 22 is filled with bydraulic fluid, the spring 51 is substantially expanded and fluid pressure, for example, air pressure in the bellows 41 pressurizes the fluid against the combined resistance of the fluid and the spring. As normal leakage occurs and fluid is supplied from the reservoir 22 to the system, air pressure forces the piston 50 downwardly against the gradually increasing resistance of the spring 51 and thus gradually decreases fluid pressure in the system from a maximum value of, for example, psi. toward the predetermined minimum value of, for example, 60 psi. By observing the reading of the pressure gage 23, the

operator can replenish the hydraulic fluid in the reservoir before pressure in the system falls below the predetermined minimum.

If desired, the spring 51 and shoulder 52 can be removed and the bellows 41 can be connected to a constant volume tank of compressed air by the air line 42, a decrease in air pressure due to the expansion of the bellows serving gradually to reduce the tank pressure and indicate the need for additional hydraulic fluid. However, the use of the spring type reservoir (Fig. 4) is preferred since a valve leak permitting flow of air into the tank from a supply source in the constant volume type might tend to maintain the system pressure even though a slow hydraulic leak existed in the system. The source 44 of air pressure and the hydraulic reservoir may be located at the control center 11 or on the truck as shown in Fig. 1.

The present system includes a pneumatic-hydraulic,

fail-safe mechanism arranged to apply and set the brake automatically should there be a failure in air pressure or a drop in hydraulic pressure below the predetermined minimum value. As shown in Fig. 2, a brake actuator is provided including a safety cylinder 55 having a piston rod 54 which is pivotally connected to an arm 56 fixed to the brake shaft 39. A compression spring 57 in the cylinder 55 bears against one side of the piston 58 in opposition to air pressure in the cylinder which normally overcomes the force of the spring 57. Upon release of the air pressure, the spring shifts the piston 58 and rotates the brake shaft 39 in a clock-wise direction to apply and set the brake.

Primary air pressure is normally connected to the cylinder 55 from the air source 44 through three serially arranged air relay valves 61, 62 and 63, a main air line 64, and branch lines 65, 66, 67 and 68, as shown in Fig. 2. The valves 61 and 62 are normally held open by the hydraulic pressure in lines 32 and 33, and are connected thereto by branch hydraulic lines 69 and 70, respectively. The valve 63 is normally held open by pilot air pressure reaching the valve from the main air line 64 through a manually operated and normally open threeway valve 71, a pilot air line 72, a normally open valve 73, and a pilot air line 74.

The construction and arrangement of the fail-safe apparatus is such that a reduction in fluid pressure in the hydraulic system below the predetermined value effects a reduction in pressure in at least one of the hydraulic branch lines 69 or 70 whereby the air relay valve (61 or 62, as the case may be) connected to the affected branch line closes and operates to block the air pressure to the cylinder 55 and simultaneously to vent the air pressure in the cylinder through the valve 63 and the closed relay valve; thus permitting the spring 57 to set the brake. A failure in either primary or pilot air pressure also permits the spring to set the brake. The orifice 25 restricts the flow of fluid from the reservoir 22 so that fluid pressure cannot be maintained above the predetermined minimum value when a sudden loss of fluid pressure occurs in the system.

The air relay valves 61, 62 and 63 may be of any suitable construction such, for example, as that shown in Fig. 3 and comprising a three-spool piston 75 housed in a cylinder 76. The piston is shiftable between limits defined by a boss 77 carried by a cap 78 and a boss 79 in the lower end of the cylinder. In Fig. 3, the valve is shown in the normally open position wherein the piston is held against the action of a spring 80 which is normally compressed by air or hydraulic pressure acting on the spool 81 through a port 82 in the cylinder wall. Also, in this position primary air communicates freely between the cylinder wall air inlet and outlet ports 83 and 84, respectively, which are disposed between the spools 85 and 86. A failure in air or hydraulicpressure as the case may be permits the spring 80 to shift the piston 75 whereby the spool 86 blocks flow through the inlet port 83 and the spool 85 subsequently opens a vent port 87 to bleed off pressure through the ports 84 and 87 to the atmosphere. The force exerted on the piston 75 by the spring may be varied according to the minimum pressure below which it is desired to set the brake. An open vent port 88 is provided to prevent a pressure buildup below the spool 86. For illustrative purposes, the valve in Fig. 3 is shown connected to the air and hydraulic lines associated with the valve 62 of Fig. 2. The air relay valves 61 to 63 inclusive, the cylinders 34 and 55 and the valve 73 and associated apparatus may be located in the housing 20 as shown in Fig. 1 or may otherwise be suitably arranged such, for example, as in the drawworks housing wherein the piston rod 54 and arm 37 can be mechanically connected to the brake shaft 39.

The valve 71 is provided as an additional way of setting the brake in case of an emergency. Preferably, this valve is located at the control center 11. In its normally open position the valve 71 permits the flow of pilot air pressure through the pilot air lines 72 and 74 and the valve 73 for holding the valve 63 open. In case of an emergency the brake is set by manually shifting the valve handle to operate the valve and block the primary air in line 64 and bleed pressure from valve 63 through the pilot air line 74, valve 73, air line 72 and a normally closed vent 71 thereby closing the valve 63 to block the air line 67 and vent the cylinder 55.

The master cylinder 28 is provided with a by-pass line 90 including at least one by-pass valve 91 which may be used for repositioning the brake lever 19. Preferably, the valves 71 and 91 are of a type having rotatable valve members. Also these valve members are preferably connected to a common operating shaft, diagrammatically indicated at 92, such that the valve 71 is automatically operated to vent the cylinder 55 when the valve 91 is opened so that the brake is automatically set whenever the by-pass line is open. A second normally closed by-pass valve 93 may be provided to adjust the position of the lever 19 and to prevent it from falling out of position when the valve 71 is operated to vent the cylinder 55 and set the brake.

Finally the valve 73 is provided with a limit switch 94 which, when depressed by the cam 38, closes the normally open valve 73 which blocks the pilot air line 72 and opens a normally closed vent 95 and bleeds the pilot should be implied therein or inferred therefrom, for it will be apparent to those skilled in the art that variations and changes may be made in the present system without departing from the spirit and scope of the appended claims. For example, while the system of the present invention has been illustrated with a mobile well-servicing unit, the system can readily be employed with the hoist of a stationary drilling rig and other apparatus.

I claim as my invention:

1. A remote control system for an oilfield hoist brake comprising a closed hydraulic circuit employing a pressurized fluid, a slave cylinder having a piston mechanically connected to the brake, a pair of conduits in said circuit connected to the slave cylinder on opposite sides of said piston whereby the piston is shiftable in opposite directions by displacement of said pressure fluid for ap-.

plying and releasing the brake, a master cylinder having a piston and a piston rod, saidconduits being connected to the master cylinder on opposite sides of its piston, a

,manually operated lever connected to said piston rod for sponsive to the fluid pressure in said circuit for operating the brake actuator to apply thebrake when the pressure in either conduit decreases below a predetermined value, a fluid reservoir for pressurizing the hydraulic circuit, supply conduits communicating between said reservoir and the master cylinder on opposite sides of the piston therein, and means restricting the passage of fluid from said reservoir to the master cylinder.

2. A remote control system for an oilfield hoist brake comprising a closed hydraulic circuit employing a pressurized fluid, a brake shaft rotatable in opposite directions for applying and releasing the brake, a slave cylinder having a piston mechanically connected for rotating said shaft, a pair of conduits in said circuit connected to the slave cylinder on opposite sides of said piston whereby the piston is shiftable in opposite directions by displacement of said pressure fluid for applying and releasing the brake, a master cylinder having a piston anda piston rod, said conduits being connected to the master cylinder on opposite sides of the piston therein, a manually operated lever connected to' said piston rod for shifting the master cylinder piston in opposite directions and displacing said pressure fluid for applying and releasing the brake, an emergency brake actuator comprising a cylinder having a piston and a piston rod mechanically connected for rotating the brake shaft and shiftable in opposite directions for applying and releasing the brake, a

spring for urging the actuator piston in one direction for applying the brake, a compressed air circuit including a source of compressed air, an air line communicating between the said source and the actuator cylinder for ap-, plying a force on the actuator piston normally overcoming the force of said spring, means responsive to the fluid pressure in the hydraulic circuit for venting the actuator cylinder when the pressure in either conduit decreases below a predetermined value, a normally closed vent in said compressed air circuit operable for venting the actuator cylinder, a limit switch for operating said vent, a cam fixed to said brake shaft and arranged to engage and operate said limit switch for opening the vent before the slave piston can reach the end limit of its stroke when the brake is applied, a pressurized fluid reservoir, supply conduits communicating between said reservoir and the master cylinder on opposite sides of the piston therein and means restricting the passage of fluid from said reservoir to the master cylinder.

References Cited in the file of this patent UNITED STATES PATENTS 498,970 Eichbaum June 6, 1893 1,696,985 Trbojevich Jan. 1, 1929 2,409,908 Simpkins Oct. 22, 1946 2,645,313 Schaadt July 14, 19531

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