Hook with pneumatic control circuit safety relief

Abstract

A load lifting hook assembly includes a body, a hook coupled to the body, a fluid connection on the body and connectable to a pressurized fluid source, a piston and a pressure relief valve. The piston is extendable from the body to engage the hook and lock the hook in a closed position relative to the body. The piston is configured to receive pressurized fluid from the fluid connection tending to urge the piston out of engagement with the hook. The pressure relief valve is positioned in the body in communication with the fluid connection and configured to prevent excess pressure in the pressurized fluid from acting on the piston.

Claims

1. A load lifting hook assembly, comprising: a body; a hook coupled to the body; a fluid connection on the body and connectible to a pressurized fluid source; a piston extendable from the body to engage the hook and lock the hook in a closed position relative to the body, wherein the piston is configured to receive pressurized fluid from the fluid connection tending to urge the piston out of engagement with the hook; and a pressure relief valve in the body positioned in communication with the fluid connection and configured to prevent excess pressure in the pressurized fluid from acting on the piston, wherein the pressure relief valve is configured to vent excess pressure at a selected pressure through an opening in the body to a surrounding area.

2. The load lifting hook of claim 1, wherein the piston is spring-biased to an extended position and the hook comprises a recess shaped to receive the piston when the hook is in a closed position.

3. The load lifting hook of claim 1, wherein the hook comprises a hook body having a base, a hook pivot axis and a distal free end defining a hook point, and wherein the pressure relief valve is positioned in the body opposite the hook point when the hook is in the closed position.

4. The load lifting hook of claim 3, wherein the hook body comprises a hook throat extending from the hook point and across a gap between the hook point and the base of the hook, and where the body comprises a pivotable latch extending away from the body and towards the hook point when the hook is in the closed position.

5. The load lifting hook of claim 4, wherein the pressure relief valve is positioned adjacent the pivotable latch.

6. The load lifting hook of claim 1, wherein the body comprises a passageway, and wherein the pressure relief valve is secured within the passageway with a retaining member.

7. The load lifting hook of claim 1, wherein the pressure relief valve comprises a spring member.

8. The load lifting hook of claim 1, wherein the selected pressure at which the pressure relief valve is configured to vent the excess pressure is selected from a range of 20 psi to 40 psi.

9. The load lifting hook of claim 1, further comprising a swivel arrangement coupled to one end of the body.

10. The load lifting hook of claim 1, further comprising a top cap removably secured to the body.

11. The load lifting hook of claim 1, further comprising a top cap removably coupled to the body, a swivel screw extending from the top cap and connecting to an exterior swivel.

12. The load lifting hook of claim 1, wherein the body defines a body axis and a bore along the body axis dimensioned to receive the piston.

13. The load lifting hook of claim 1, wherein the hook is pivotably coupled to the body.

14. The load lifting hook of claim 1, wherein when the load lifting hook assembly is under a hook load greater than 60 lbs., then the selected pressure at which the pressure relief valve is configured to vent the excess pressure can be selected from a range of 20 psi to 60 psi.

15. A load lifting hook system, comprising: multiple load lifting hooks; at least one manifold configured to supply at least two of the multiple load lifting hooks with pressurized fluid via an individual conduit extending to a fluid connection on a body of each load lifting hook, respectively; a solenoid valve positioned upstream of the at least one manifold; a pressurized fluid source providing a source of pressurized fluid; a regulator positioned downstream of the pressurized fluid source, the regulator being adjustable to adjust a supply pressure of the pressurized fluid supplied by the pressurized fluid source; and a pressure relief valve positioned at each of the multiple load lifting hooks and remote from the regulator, wherein the pressure relief valve is selectively configured to vent excess pressure above a predetermined limit pressure that is independent of the supply pressure set by the regulator.

16. The load lifting hook system of claim 15, wherein the pressure relief valve is housed within the body of each load lifting hook in communication with the fluid connection.

17. The load lifting hook system of claim 15, wherein the pressure relief valve is secured in the body with a tamper resistant arrangement.

18. The load lifting hook system of claim 15, wherein the pressure relief valve is non-adjustable.

19. A load lifting hook system, comprising: a load lifting hook having a fluid connection; one or more conduit segments connecting the fluid connection of the load lifting hook with a pressurized fluid source providing a source of pressurized fluid; a solenoid valve positioned upstream of the load lifting hook; a regulator positioned downstream of the pressurized fluid source, the regulator being adjustable to adjust a supply pressure of the pressurized fluid supplied by the pressurized fluid source; and a pressure relief valve positioned at the load lifting hook and remote from the regulator, wherein the pressure relief valve is selectively configured to vent excess pressure above a predetermined limit pressure that is independent of the supply pressure set by the regulator.

20. The load lifting hook system of claim 19, wherein the pressure relief valve is secured in a body of the load lifting hook with a tamper resistant arrangement and is non-adjustable.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a perspective view of a load lifting hook according to one implementation, which is shown in isolation.

(2) FIG. 2 is a right side elevation view of the load lifting hook of FIG. 1.

(3) FIG. 3 is a top plan view of the load lifting hook of FIG. 1.

(4) FIG. 4 is a left side elevation view, shown partially in section, of the load lifting hook of FIG. 1.

(5) FIG. 5 is a section view in elevation of the load lifting hook taken along the line V-V in FIG. 3.

(6) FIG. 6 is a section view in elevation of the load lifting hook taken along the line VI-VI in FIG. 2.

(7) FIG. 7 is a schematic control diagram showing multiple load lifting hooks configured in a load lifting hook system.

DETAILED DESCRIPTION

(8) Described below are implementations of a load lifting hook used for lifting cargo that is releasable by fluid actuation (typically, pneumatic actuation), and has a built-in or integrated pressure relief valve (or other pressure releasing device) configured to vent excess pressure supplied to the load lifting hook to prevent release of the hook under conditions outside of a specified design range(s).

(9) Referring to FIGS. 1-6, a first implementation of the load lifting hook 100 has a body 102 and a hook member 104 pivotably connected to the body 104 at a hook pin 106. In the illustrated implementation, a proximal end of the body 102 is fitted with a removable top cap 108.

(10) A swivel attachment 110 is coupled to top cap 108. The swivel attachment 110 has a chain pin 140 for coupling the load lifting hook to another rigging component, such as a lifting cable or chain (not shown). The chain pin 140 can be retained by a roll pin 132 (FIG. 6). The swivel attachment 110 can be configured to allow rotation relative to the body 102 over a selected angular range.

(11) The load lifting hook 100 can be fitted with a latch 112 as shown that extends towards the hook 104 to close a throat of the hook 104 when it is the closed position as shown in FIGS. 1-6. The latch 112 can be mounted to the body 102, such as to pivot about a latch pin 114 coupled to the body 102. The latch 112 may be spring biased by a latch spring 134 (FIG. 4) to its closed position as shown in FIGS. 1-6.

(12) Referring to the section views of FIGS. 5 and 6 in greater detail, the interior construction of the load lifting hook 100 can be described. A swivel bolt 124, which can be arranged to extend along a body axis of the load lifting hook 100 within an interior recess 115 as shown, couples the swivel attachment 110 to the top cap 108. A swivel bolt washer 126 can be positioned beneath the head of the swivel bolt 124 as shown. The swivel bolt 124 can be adjustable to adjust an angular range over which the swivel attachment 110 can rotate. A seal 125 is provided in a bore for the swivel bolt 124 to seal against debris and water entering into body.

(13) In the illustrated implementation, the top cap 108 is removably coupled to the body 102, such as with the four cap bolts 128. The cap bolts 128 can be fitted with locking tabs 130 (FIG. 6) to prevent inadvertent loosening of the cap bolts 128. In other implementations, a single-piece body construction could be used.

(14) A piston 116 (also sometimes referred to as a “lock member”) is arranged within the recess 115 in the body 102. The piston 116 is shown in its extended position “locked” position) with its distal end extending through an end of the body 102 and into a recess 117 of the hook 104, thus locking the hook 104 in the closed position as shown. The piston 116 is spring-biased to the locked position as shown by a spring 122 that is also positioned in the recess 115. There is a seal 118 mounted in a bore to seal a shaft of the piston 116. There is another seal 120 mounted on a head of the piston 116 to seal it within a cylinder portion of the recess 115.

(15) In operation, a fluid conduit (such as a conduit 180 as shown in FIG. 7) is connected to the body 102 of the load lifting hook, e.g., at a port opening 160 (FIGS. 1, 3 and 5), to provide pressurized air or other pressurized fluid to operate the piston. The pressurized fluid is supplied to the piston via a supply passageway 156. If the supplied pressure is sufficient to overcome the force of the spring 122, then the piston 116 is urged upward into a retracted position, and the hook 104 moves from the closed position to an open position.

(16) If the pressurized fluid supplied to the load lifting hook is at a supply pressure (e.g., 100 psi) above a predetermined operating pressure for the load lifting hook (e.g., 30-40 psi), then under certain circumstances the piston 116 could be moved and disengaged from the hook 104 while the hook 104 is at least partially loaded. Such circumstances could lead to injury to personnel and damage to the cargo, lifting equipment and surroundings, and thus also disrupt and delay operations.

(17) In the lifting hook 100, however, there is a pressure relief valve 148 that is positioned in communication with the pressurized fluid supplied at 160. In the illustrated implementation, the pressure relief valve 148 is arranged at an end of an exhaust passageway 158 formed in the body 102 that intersects the supply passageway 156. The pressure relief valve 148 exhausts excess supply pressure above the predetermined operating pressure to the atmosphere, thus subjecting the piston 116 to only the operating pressure. As a result, if excess pressure is supplied in an effort to release the hook 104 outside of predetermined conditions, then the excess pressure is exhausted, and the hook 104 will remain locked in the closed position.

(18) The pressure relief valve 148 in the illustrated implementation includes a valve pin 150 that is biased to a closed position by a compression spring 152. The valve pin 150 and the compression spring 152 are secured in place to cover an exhaust opening in the exhaust passageway 158 by a retaining ring 154. The components of the pressure relief valve are recessed from exterior surfaces of the load lifting hook 100 and thus are protected from damage that might occur when the load lifting hook contacts other objects during use. In the illustrated implementation, the pressure relief valve 148 is at least partially hidden by the latch 112. In addition, the pressure relief valve 148 cannot be easily dismantled in the field and thus is tamper-resistant, which keeps the pressure relief valve 148 in service to actively protect personnel and property within traditional industry standards while the load lifting hook 100 is in use.

(19) In one implementation, the pressure relief valve is a Generant VRV-125B-V-35 valve available from Generant Inc. (see www.generant.com), which has a ⅛″ port, is made of brass, has a seal made of VITON™, and has a nominal set pressure of 35 psig. In other implementations, any one or more of these valve parameters can be varied to suit specific operating requirements. In addition, in still other implementations, a custom pressure relief valve or other pressure releasing/relief device can be used. For example, in other implementations described below, desired results are achieved with pressure release valves having a nominal set pressure from 20 psi to 40 psi.

(20) In a first example, testing was performed on a conventional (unmodified) Cranston Unihook Model 26A097 to determine a baseline of hook loads and hook release pressures that may cause the hook to open without actuation. A crane scale was installed in the Cranston Hook Pull Test Fixture to determine the weight (force) readings corresponding to the readings of the Hook Pull Test Fixture. The test hook was installed into the Hook Pull Test Fixture. The hook release pressure was then varied over different hook loads, and the results were recorded, noting whether the hook opened or stayed closed (Table 1).

(21) TABLE-US-00001 TABLE 1 Hook Load Release Pressure Hook Release? (PSI) (PSI) Yes/No 35 lbs 35 Yes (5 psi) 40 Yes 45 Yes 50 Yes 55 Yes 60 Yes 60 lbs 35 No (5.5 psi) 40 No 45 No 50 Yes 55 Yes 60 Yes 80 lbs 35 No (6 psi) 40 No 45 No 50 No 55 No 60 Yes 100 lbs 35 No (6.5 psi) 40 No 45 No 50 No 55 No 60 No

(22) Thus, as shown in Table 1, the test hook did open at certain combinations of hook load and release pressure, particularly when under the lowest hook load of 35 lbs.

(23) In a second example, testing was conducted using modified hooks having a pressure relief valve. Both a custom designed and manufactured pressure relief valve, as well as a third party purchased pressure relief valve were tested. For the results shown below in Table 2, a Generant VRV-125B-V-35 pressure relief valve was installed in a modified body of a Cranston Unihook, Model 26A097, hook. The pressure relief valve was tested using its factory pre-set release pressure setting of 35 psi. Results were compared to the baseline testing described for hook opening vs. staying closed conditions.

(24) TABLE-US-00002 TABLE 2 Hook Load Release Pressure Hook Release? (PSI) (PSI) Yes/No 35 lbs 35 No (5 psi) 40 No 45 No 50 No 55 No 60 No 60 lbs 35 No (5.5 psi) 40 No 45 No 50 No 55 No 60 No 80 lbs 35 No (6 psi) 40 No 45 No 50 No 55 No 60 No 100 lbs 35 No (6.5 psi) 40 No 45 No 50 No 55 No 60 No

(25) Desirably, the results of Table 2 show that the hook fitted with the pressure release valve did not open under any of the combinations of hook load and release pressure. Thus, the hook fitted with a pressure release valve, and specifically a pressure release valve set at 35 psi, prevented the hook from opening while under load, including the low loads.

(26) In the first and second examples, testing was conducted on a static bench test where the precise pneumatic pressures are applied to maintain an axial lift that is controlled to be exactly vertical.

(27) By way of contrast, in a third example, testing was completed to compare unmodified and modified hooks under a dynamic (live load) condition with a typical overhead hoist and typical shackles, which more closely resembles conditions of actual use in the field.

(28) Desirably, as shown in Table 3 below, the modified hook did not undesirably open except at the lightest live load tested (60 lbs.), and only for the three highest pressures (40 psi, 50 psi and 60 psi). In contrast, the unmodified (conventional) hook opened under at least the highest pressures at all live loads that were tested. Further, the unmodified hook opened at all pressures for the two lightest live loads that were tested. Thus, the modified hook can be fitted with a pressure relief valve having a selected nominal set pressure of 20 psi to 40 psi to achieve desired release operation over a wide range of lifting conditions compared to an unmodified hook.

(29) TABLE-US-00003 TABLE 3 Unmodified Modified Hook Hook without with Pressure Live Input Relief Valve Relief Valve Load Pressure Released? Yes/No Released? Yes/No  60 lbs* 20 psi Yes No 30 psi Yes No 40 psi Yes Yes 50 psi Yes Yes 60 psi Yes Yes  70 lbs* 20 psi Yes No 30 psi Yes No 40 psi Yes No 50 psi Yes No 60 psi Yes No 80 lbs 20 psi No No 30 psi Yes No 40 psi Yes No 50 psi Yes No 60 psi Yes No 90 lbs 20 psi No No 30 psi No No 40 psi Yes No 50 psi Yes No 60 psi Yes No 100 lbs  20 psi No No 30 psi No No 40 psi Yes No 50 psi Yes No 60 psi Yes No

(30) FIG. 7 is a schematic diagram of a load lifting hook system 200 with multiple load lifting hooks 100 controlled by an operator at a centralized control station. The centralized control station may be located at some distance, even hundreds of feet (e.g., 300 feet obstructed view up to 1000 ft line of sight), from the load lifting hooks 100, the associated cargo and personnel carrying out the fastening and unfastening of load lifting hooks to and from cargo. As shown in FIG. 7, for a representative system of twelve hooks, groups of four hooks can be connected via their individual conduits 180 to manifolds 210. The manifolds 210, which are interconnected in the illustrated implementation, are in turn connected via a supply line to a solenoid valve 220. The solenoid valve 220 controls the flow of pressurized fluid (such as, e.g., air or nitrogen) to the manifolds 210 and in turn the load lifting hooks 100, thus serving to release and lock and the hooks. The solenoid valve 220 is controlled by an operator, e.g., using a remote radio transmitter with a button or other actuator. The solenoid valve 220 can also be controlled manually, e.g., if a striker plate or other device on the solenoid valve 220 is manually actuated.

(31) The solenoid valve 220 is connected to a pressurized fluid source, such as an air tank 230. In the illustrated implementation, there are two air tanks 230, which are typically configured for use in series with a second of the two tanks being connectable by a quick-connect fitting. Each air tank has an air regulator 240 that is adjustable, typically by the system operator, to adjust the pressure at the air tank 230 at which air or other fluid is supplied. An optional lubricator 250 may be positioned in the circuit to inject oil or other lubricant into the pressurized fluid to lubricate the components of the system 200.

(32) In view of the many possible embodiments to which the principles of the disclosed invention may be applied, it should be recognized that the illustrated embodiments are only preferred examples of the invention and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims. We therefore claim as our invention all that comes within the scope and spirit of these claims.