AU2008202616A1

AU2008202616A1 - System and method for fail-safe mechanical connection

Info

Publication number: AU2008202616A1
Application number: AU2008202616A
Authority: AU
Inventors: Bradley Thomas Inman
Original assignee: BRADLEY INMAN
Current assignee: BRADLEY INMAN
Priority date: 2007-09-10
Filing date: 2008-06-13
Publication date: 2009-03-26
Anticipated expiration: 2028-06-13
Also published as: AU2008202616B2

Description

P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "SYSTEM AND METHOD FOR FAIL-SAFE MECHANICAL CONNECTION" The following statement is a full description of this invention, including the best method of performing it known to me/us: 00

TITLE

SSYSTEM AND METHOD FOR FAIL-SAFE MECHANICAL CONNECTION

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FIELD OF THE INVENTION 5 The present invention relates to locking mechanisms for mechanical O connections. In particular, although not exclusively, the invention relates to a Ssystem and method for a fail-safe, hydraulically-actuated mechanical connection 0 of an implement to a heavy equipment vehicle.

BACKGROUND TO THE INVENTION The safe operation of heavy equipment machines such as bulldozers, excavators, front-end loaders, skid-steer loaders and integrated tool carriers (ITCs) requires all tools or implements attached to the machines to be properly secured using an intended attachment mechanism. If implements are not properly secured, their accidental release from a machine can be disastroussometimes resulting in damage to expensive property, or even the severe injury or death of nearby workers. However, many such attachment mechanisms for heavy machine implements, such as buckets or rippers, are not fail-safe. The diligence of well-trained operating personnel, and other "low-order" safety controls, are thus necessary to ensure the secure attachment and safe use of such implements.

"Low-order" safety controls concerning the operation of heavy equipment can include training programs for workers, documented procedures and work instructions, audits and inspections, and worker supervision practices. However, such controls are generally not considered fail-safe, as human error can still result in unsafe equipment operation. Thus fail-safe, "high-order" safety controls are generally preferred over "low-order" safety controls.

"High-order" safety controls concerning the operation of heavy equipment can include passive engineering controls that prevent equipment from functioning if safety mechanisms are not properly applied, or if equipment is 00 operated outside of accepted operating parameters-such as at excessive c speed or when overloaded.

;ZNumerous prior art patents describe various mechanisms for providing t' high-order safety controls for industrial equipment. For example, US patent no.

6,241,258 to Roussel, titled "Method of Controlling Clamping and Unclamping of Sa Hydraulic Chuck", discloses controlling a clamping pressure in accordance with Sa clamping pressure set point applied to at least one chamber of an actuator.

0Clamping pressure is then maintained in a corresponding chamber if the control

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oO pressure upstream of the actuator suddenly falls due to a machine malfunction.

US patent no. 5,169,277 to Orser et al., titled "Lift Arm Lock Down Apparatus and Method", discloses a lock down apparatus for a load lifting vehicle that prevents accidental lifting of a control lever when an operator is entering or exiting the vehicle.

US patent no. 4,783,106 to Nutter, titled "Method and Apparatus for Automatically Controlling Pressure in Fluid-Actuated Systems", discloses controlling the level of a clamping pressure applied by a clamp to a load.

Through the use of a number of controllable fluid discharge systems, the clamping pressure is automatically increased in increments depending upon the resistance of a load to the clamping pressure exerted.

US patent publication no. 2005/0040224 to Brinton et al., titled "System and Process to Record Inspection Compliance Data", discloses a handheld portable reader that is used to generate and store data that indicate that an equipment operator was sufficiently close to each of a plurality of components during an inspection to adequately inspect the components. Radio frequency identification (RFID) tags are placed on the components, and the reader can write data to and read data from the tags.

Integrated tool carriers (ITCs) are self-propelled machines that generally include an integral, front-mounted implement-supporting boom, and a linkage having an integral quick coupler. ITCs are versatile machines that can perform a wide range of tasks including mixing, stripping, spreading, loading, cutting, boxing, backfilling, lifting and carrying materials and equipment. These tasks are 00 O performed using various types of implements that are connected to the integral N quick coupler. Such implements include, for example, augers, power rotary ;brooms, asphalt cutters, angle blades, drills, straight blades, hydraulic hammers and rippers. Other types of heavy equipment, such as bulldozers and front-end loaders, are also frequently adapted to use a wide range of implements such as buckets, scoops, scrapers, rippers, rams, and hammers.

(The prior art discloses various mechanisms for securely attaching such cimplements. These mechanisms include, for example, hydraulic/pneumatic 00 C locking hubs, clamps, keyed pins, and other mechanical keys. However, such mechanisms generally require low-order safety controls to ensure that the implements are properly and safely secured before being operated. The prior art use of high-order, fail-safe mechanisms have generally been limited to either crude mechanical lock-out mechanisms, or high-technology electronics equipment such as electronic eyes and electronic position sensors.

Mechanical lock-out mechanisms can be undesirable because they often require an operator to leave an operating cab of, for example, a bulldozer, and manually move the lock-out mechanisms to add or remove an implement. Thus, in addition to being inconvenient, such mechanisms also can be dangerous as the operators can be exposed to injury when outside of their cab at, for example, a busy worksite. On the other hand, high-technology electronics equipment can be fragile, and is often unsuitable for the harsh and dirty environments in which heavy equipment implements are frequently used. There is therefore a need to overcome or alleviate deficiencies in the prior art concerning high-order safety controls and, in particular, fail-safe mechanical connections of heavy equipment implements.

OBJECTS OF THE INVENTION Therefore, an object of some embodiments of the present invention is to overcome or alleviate one or more limitations of the prior art, including providing an improved fail-safe mechanical connection.

Another object of some embodiments of the present invention is to 00 O provide an improved fail-safe mechanical connection using only two pressurised N fluid hoses to clamp, unclamp, and detect a secure closure of, the mechanical connection.

Another object of some embodiments of the present invention is to reduce a pressure of a fluid circuit of a machine below an operating pressure when a Imechanical connection is not properly secured.

IA further object of some embodiments of the present invention is to

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0provide heavy equipment manufacturers and designers with a commercial 00 0choice or a useful alternative. Still further objects will be evident from the 0 following detailed description.

SUMMARY OF THE INVENTION According to one aspect, the present invention is a system for securing a mechanical connection, comprising: a clamping element operatively controlled by a clamping actuator; a locking element operatively controlled by a locking actuator; a switching valve operatively connected to the locking element; and a fluid circuit having a first fluid line and a second fluid line both in fluid communication with the clamping actuator, the locking actuator, the switching valve, and a main power circuit; wherein providing fluid pressure in the first line of the fluid circuit causes the locking actuator to unlock the locking element and actuate the switching valve, and subsequently causes the clamping actuator to unclamp the clamping element; and wherein providing fluid pressure in the second line of the fluid circuit causes the clamping actuator to clamp the clamping element, and subsequently causes the locking actuator to move the locking element to a locked position and actuate the switching valve.

7- 00 O Preferably, fluid pressure to the main machine fluid circuit is reduced by N the switching valve when the locking element is not in the locked position.

;Preferably, the fluid circuit and the main power circuit are hydraulic circuits.

Optionally, the fluid circuit and the main power circuit are pneumatic Icircuits.

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N Preferably, the mechanical connection is adapted for securing an N implement or tool to a vehicle.

00 oO SPreferably, the system is mounted on one of the following vehicles: an integrated tool carrier (ITC), bulldozer, excavator, front-end loader, or skid-steer loader.

Preferably, the fluid circuit comprises a pilot oil supply valve controlled by a bypass switch.

Preferably, the locking element comprises a safety pawl.

Preferably, the fluid circuit comprises a counter balance valve in fluid connection with the switching valve.

Preferably, the fluid circuit comprises a pressure sequence valve in fluid connection with the clamping actuator.

Preferably, the fluid circuit comprises a clamp control valve that controls fluid pressure in the first line and the second line.

According to another aspect, the present invention comprises a method for securing a mechanical connection. The method comprises the following steps: activating a bypass switch to operate a pilot oil supply valve and provide fluid pressure to a switching valve; actuating a counter balance valve using pressure provided through the switching valve, whereby pressure in a main power circuit is maintained below an operating pressure; actuating a clamp control valve to cause both clamping of a clamping element and locking of a locking element; actuating the switching valve in response to the locking of the locking element; and providing the operating pressure in the main power circuit in response to actuating the switching valve.

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BRIEF DESCRIPTION OF THE DRAWINGS STo assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention are described below by way of example only with reference to the accompanying drawings, in which: N FIG. 1 is a simplified schematic diagram illustrating components of a

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N system for securing a mechanical connection, according to some embodiments 00 Oof the present invention; FIG. 2 is a diagram illustrating a side perspective view of the system of FIG. 1 in the form of a "quick-hitch" module for use with an integrated tool carrier (ITC), according to some embodiments of the present invention; FIG. 3 is a diagram illustrating a top perspective view of the "quick-hitch" module of FIG. 2; FIG. 4 is a diagram illustrating a further side perspective view of the "quick-hitch" module of FIG. 2, shown attached to a boom of an ITC; and FIG. 5 is a schematic diagram illustrating electric and hydraulic elements associated with a system for securing a mechanical connection, according to some embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention comprise a system and method for securing a mechanical connection. Elements of the invention are illustrated in concise outline form in the drawings, showing only those specific details that are necessary to understanding the embodiments of the present invention, but so as not to clutter the disclosure with excessive detail that will be obvious to those of ordinary skill in the art in light of the present description.

In this patent specification, adjectives such as first and second, left and right, front and back, top and bottom, etc., are used solely to define one element or method step from another element or method step without necessarily 00 requiring a specific relative position or sequence that is described by the C adjectives. Words such as "comprises" or "includes" are not used to define an exclusive set of elements or method steps. Rather, such words merely define a

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minimum set of elements or method steps included in a particular embodiment of the present invention.

IDReferring to FIG. 1, a simplified schematic diagram illustrates components of a system 100 for securing a mechanical connection, according to some

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Sembodiments of the present invention. A clamping element 105 is actuated by a 00 rod 110 connected to a clamping actuator in the form of a hydraulic clamp 00 cylinder 115. A locking element in the form of a safety pawl 120 is actuated by a rod 125 connected to a locking actuator in the form of a hydraulic lock cylinder 130. The clamping element 105, clamp cylinder 115, safety pawl 120, and lock cylinder 130 are secured to a machine (not shown) such as an integrated tool carrier (lAC). In use, the clamping element 105 rotates about a pivot point 135 to securely connect to the machine a locking pin 140 of an implement (not shown) such as a bucket or other tool. When the clamp cylinder 115 is fully extended as shown, thus placing the clamping element 105 in a clamped position, the lock cylinder 130 also can be fully extended as shown. That positions the safety pawl 120 in a locked position adjacent a shoulder 145 of the clamping element 105. Similar to the function of conventional safety pawls that are well known in the art, when the safety pawl 120 is locked adjacent the shoulder 145, the clamping element 105 is unable to rotate about the pivot point 135 to return to an unclamped position, because the shoulder 145 will bind against an end of the safety pawl 120. Only when the lock cylinder 130 is retracted, which rotates the safety pawl 120 about a pivot point 150 and moves the safety pawl 120 away from the shoulder 145 to an unlocked position, is the clamp cylinder 115 able to move the clamping element 105 to an unclamped position. When the clamping element 105 is in an unclamped position, the locking pin 140 and its associated implement then can be released from the machine.

According to the teachings of the present invention, a switching valve in the form of a hydraulic pressure reducing valve 155 is operatively connected to the safety pawl 120. The hydraulic pressure reducing valve 155 ensures that 00 O only when the safety pawl 120 is in a locked position--which means that the N clamping element 105 is in a clamped position--is an operating hydraulic pressure of the machine able to rise above a pilot pressure value to a full operating pressure value. That effectively renders the machine inoperable unless and until the clamping element 105 is in a fully clamped position. When used with effective implement attachment designs, when the clamping element 105 is in a fully clamped position one of two conditions is satisfied: either 1) no Cimplement is attached to the machine, and thus the machine can be safely Ooperated without an attached implement; or 2) an implement is properly and 00 securely attached to the machine so that the machine can be safely operated.

Referring to FIG. 2, a diagram illustrates a side perspective view of the system 100 in the form of a "quick-hitch" module for use with an integrated tool carrier (ITC), according to some embodiments of the present invention. The "quick-hitch" module includes a base 205 for attaching to the module to the ITC.

A fixed-position clamping arm 210 is used for clamping to an implement. The clamping element 105 is shown as rotatable about the pivot point 135 in response to movement of the rod 110.

Referring to FIG. 3, a diagram illustrates a top perspective view of the "quick-hitch" module of FIG. 2. Many of the elements of the system 100 are visible, including various hydraulic hoses used to power the hydraulic clamp cylinder 115 and the hydraulic lock cylinder 130. The safety pawl 120 and the hydraulic pressure reducing valve 155 are also shown.

Referring to FIG. 4, a diagram illustrates a further side perspective view of the "quick-hitch" module of FIG. 2, shown attached to a boom 405 of an ITC.

The "quick-hitch" module is shown inverted relative to the diagram shown in FIG.

2. The boom 405 of the ITC is shown suspending the system 100 of the quick hitch module above an implement 400 that can be attached to the ITC using the system 100. To attach the implement 400, the boom 405 is lowered by an operator of the ITC so that the fixed-position clamping arm 210 is secured around an implement first locking pin 410. Next, with the hydraulic clamp cylinder 115 fully retracted so that the clamping element 105 is in a fully unclamped position, the system 100 is further lowered so that the clamping element 105 is adjacent an implement second locking pin in the form of the 00 O locking pin 140. The hydraulic clamp cylinder 115 is then extended so that the 0 N clamping element 105 engages the locking pin 140, which safely and properly ;secures the implement 400 to the system 100, and thus indirectly to the boom 405 of the ITC.

After the clamp cylinder 115 is fully extended, the lock cylinder 130 also Ican be extended so that the safety pawl 120 engages the clamping element 105 adjacent the shoulder 145. When the safety pawl 120 is moved to this locked

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position, the hydraulic pressure reducing valve 155 then enables a full operating 00 system pressure to be supplied to the operating elements of the ITC so that the Simplement 400 can be used. If the lock cylinder 130 is unable to fully extend, it likely means that the safety pawl 120 is bound against the clamping element 105 because the clamping element 105 is not in a fully clamped position. The pressure reducing valve 155 will therefore prevent full operating system pressure from being supplied to the operating elements of the ITC, thus providing a failsafe, "high-order" safety control for the ITC. Further details of specific embodiments of the system 100 are described below.

Referring to FIG. 5, a schematic diagram illustrates electric and hydraulic elements associated with the system 100 for securing a mechanical connection, according to some embodiments of the present invention. For example, consider that the electric and hydraulic elements shown in FIG. 5 are components of an integrated tool carrier (ITC) that employs the system 100.

When an operator starts the ITC and intends to connect an implement, such as the implement 400, to the system 100, a main hydraulic pump (not shown) of the ITC supplies hydraulic fluid to a main hydraulic line 505. A pilot oil supply valve 510 is biased open to a pump pilot pressure configuration shown, so that oil from the main hydraulic line 505 flows directly to a sump 513. The operator therefore engages a hydraulic neutral switch 515, which are well known by those having ordinary skill in the art, and then manually activates an electric bypass switch 520. The bypass switch 520 is biased open so that, for example, the switch 520 must be manually held in to maintain a closed circuit from a power supply 525 to an electric solenoid 530 attached to the pilot oil supply valve 510.

The pilot oil supply valve 510 is biased open so that if power is lost to the electric solenoid 530 then the pilot oil supply valve 510 will open. Activation of 00 0 the solenoid 530 causes the pilot oil supply valve 510 to close. Oil therefore c flows from the main hydraulic line 505 through a check valve 535, through a Sclamp control valve 540 (shown in a clamped configuration), and to a port of the hydraulic pressure reducing valve 155. Consider that the lock cylinder 130 has not fully extended, which means that the safety pawl 120 is not in a securely locked position. The hydraulic pressure reducing valve 155 will therefore be in the unlocked position shown in FIG. 5, enabling oil to flow through the valve 155, c from the port to an port to an "S2" port, and to a counter balance valve c 545 (shown closed). Oil will also flow through a "V2" port and urge both the 00oo Sclamp cylinder 115 and the lock cylinder 130 to fully clamped and locked Spositions, respectively. However, because the pressure reducing valve 155 remains in the unlocked position, it means that the clamping element 105 is still unsecured. For example, the clamping element 105 may be stuck in a partially clamped position because it is bound against the locking pin 140 of the implement 400. The implement 400 is therefore not properly secured to the boom 405 of the ITC.

When the hydraulic pressure at the "S2" port exceeds a predetermined threshold (such as a pilot pressure of 500psi), the counter balance valve 545 opens and oil flows from the "V2" port, through the counter balance valve 545, through a check valve 550, through a port "VI" and back through the clamp control valve 540 to a sump 555. A pressure in the main hydraulic line 505 therefore cannot exceed a pilot pressure value.

Using the hydraulic pilot pressure, if the operator is able to manoeuvre the boom 405 of the ITC so that the clamping element 105 can be moved by the clamp cylinder 115 to a fully clamped position, which securely clamps the implement 400 to the boom 405, the safety pawl 120 also will be moved by the lock cylinder 130 to a fully locked position. The ITC will therefore be ready to be operated safely. Extension of the clamp cylinder 115 causes oil to return from the clamp cylinder 115, through a check valve 553, through the "VI" port, through the clamp control valve 540, and to the sump 555. Similarly, extension of the lock cylinder 130 causes oil to return from the lock cylinder 130 through the "VI" port, through the clamp control valve 540, and to the sump 555.

00 In a fully locked position, the safety pawl 120 will mechanically switch the C pressure reducing valve 155 so that the port deadheads at a port.

;Pressure at the "S2" port will therefore drop and the counter balance valve 545 t' will return to the closed position (as shown). A port at the counter balance valve 545 then can drain through a port of the pressure reducing valve 155 and to the sump 555. Oil pressure in the main hydraulic line 505, and at a "GI" test port, will therefore rise to a full operating pressure (such as 2600psi). A pressure switch 557 closes when the pressure in the main hydraulic line 505 00exceeds a threshold pressure (such as 2000psi). Because the hydraulic neutral 00 Sswitch 515 is already closed, a parallel circuit between the power supply 525 and the electric solenoid 530 is then established. That enables the operator to release the bypass switch 520 and still maintain the pilot oil supply valve 510 in a closed configuration. The main hydraulic line 505 remains at an operating pressure and the operator can use both hands to operate the ITC. The main hydraulic line 505 therefore can provide hydraulic pressure to operate the ITC and manipulate the boom 405 and the implement 400.

Next, when the operator decides to remove the implement 400 from the boom 405, the operator toggles a clamp switch 560 to an unclamp position, which activates a solenoid 565 that moves the clamp control valve 540 to an unclamped configuration. (Note that if power is lost to the clamp switch 560, the clamp control valve 540 will remain in its current configuration, whether clamped or unclamped.) When the clamp control valve 540 is moved to an unclamped configuration that immediately causes pressure at the pressure switch 557 to drop, thus opening the pressure switch 557 and in turn opening the pilot oil supply valve 510. The operator therefore needs to again depress the bypass switch 520, which re-closes the pilot oil supply valve 510. Oil then flows through the clamp control valve 540, through the "VI" port, and deadheads at the check valve 550, at a pressure sequencing valve 570 and at the check valve 553.

Pressure in the line between the "VI" port and the pressure sequencing valve 570 therefore causes the lock cylinder 130 to retract, which pulls the safety pawl 120 to an unlocked position, and simultaneously returns the pressure reducing valve 155 to an unlocked position (as shown). As the lock cylinder 130 retracts, 00 C oil returns from the lock cylinder 130 through the "V2" port, through the clamp c control valve 540, and to the sump 555.

;The operating pressure at the "GI" port drops to a near ambient pressure Simmediately upon movement of the clamp control valve 540 to the unclamped configuration. However, after the lock cylinder 130 is fully retracted, oil provided IDthrough the "VI" port will deadhead at the lock cylinder 130. Pressure therefore will build at a port of the pressure sequence valve 570 to a threshold value

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(such as 200psi). That causes the pressure sequence valve 570 to open. A port o00 of the pressure sequence valve 570 enables a nominal amount of oil to drain from pressure sequence valve 570 when the valve 570 is opened. Oil then flows through the pressure sequence valve 570 (from the port to the port and causes the clamp cylinder 115 to retract. Retraction of the clamp cylinder 115 causes oil to flow through the "V2" port, through the clamp control valve 540, and to the sump 555. After the clamp cylinder 115 is fully retracted, pressure will again rise in the main hydraulic line 505 and at the pressure switch 557 until the pressure switch 557 closes at approximately 2000psi). That enables the operator to release the bypass switch 520 and operate the ITC.

The above described operation of the pressure sequence valve 570 thus ensures that the lock cylinder 130 is fully retracted, so that the safety pawl 120 is fully unlocked, before retracting the clamp cylinder 115 and unclamping the clamping element 105. That ensures that the clamping element 105 does not bind against the safety pawl 120 and prevent retraction of both the lock cylinder 130 and the clamp cylinder 115.

A mechanical enclosure 580 is used to house the counter balance valve 545, the check valve 550, the pressure sequence valve 570, and the check valve 553 in the system 100. For example, the mechanical enclosure 580 can be mounted on the "quick-hitch" module shown in FIG. 2. Ports on the mechanical enclosure 580, including the "S2" and "GI" ports, as well as two ports to each of the clamp cylinder 115 and the lock cylinder 130, enable hydraulic lines to pass through the mechanical enclosure 580. By mounting the mechanical enclosure 580 near the clamp cylinder 115 and the lock cylinder 130, lengths of hydraulic hosing can be conserved, and concomitant risks of leaks and hose damage are reduced.

00 a Various other embodiments and modifications of the present invention are i also enabled by the present disclosure. For example, those skilled in the art will readily appreciate that various reconfigurations of the schematic diagram shown in FIG. 5 are possible, while still accomplishing the features and functions of the present invention for securing a mechanical connection as described herein.

Further, those skilled in the art will appreciate that various embodiments of the present invention can employ pneumatic or hydraulic controls and actuators. For c example, the system 100 can be attached to various hydraulic or pneumatic 0 machines such as bulldozers, excavators, front-end loaders, skid-steer loaders, oo integrated tool carriers (ITCs), pneumatic robots, and the like. Thus the system 100 can be used to secure attachment of various implements and tools, such as augers, power rotary brooms, asphalt cutters, angle blades, drills, straight blades, hydraulic hammers, buckets, scoops, scrapers, rippers, rams and the like.

Advantages of some embodiments of the present invention thus include enabling high-order, passive control over the secure mechanical connection of an implement to a machine. For example, only two robust hydraulic lines connected to hydraulic cylinders and a pressure reducing valve can be provided at a working boom of an ITC to enable 1) clamping, 2) unclamping, and 3) detection of a secure closure of, a mechanical connection of an implement at a distal end of the working boom. Thus less robust and more fragile electrical or electronic devices, such as electrical solenoids and electronic sensors, are not required to be exposed to the often dirty and harsh environments near such mechanical connections.

The above description of various embodiments of the present invention is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the invention to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present invention will be apparent to those skilled in the art of the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. This patent specification is intended to embrace all alternatives, modifications and variations of the present 14 00 0 invention that have been discussed herein, and other embodiments that fall c1 within the spirit and scope of the above described invention.

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Claims

2. The system according to claim 1, wherein fluid pressure to the main machine fluid circuit is reduced by the switching valve when the locking element is not in the locked position.
3. The system according to claim 1, wherein the fluid circuit and the main power circuit are hydraulic circuits.
4. The system according to claim 1, wherein the fluid circuit and the main power circuit are pneumatic circuits. 00 The system according to claim 1, wherein the mechanical connection is c adapted for securing an implement or tool to a vehicle. ;Z The system according to claim 1, wherein the system is mounted on one of the following vehicles: an integrated tool carrier (ITC), bulldozer, excavator, Sfront-end loader, or skid-steer loader. C- 00oo 7. The system according to claim 1, wherein the fluid circuit comprises a pilot oil supply valve controlled by a bypass switch.
8. The system according to claim 1, wherein the locking element comprises a safety pawl.
9. The system according to claim 1, wherein the fluid circuit comprises a counter balance valve in fluid connection with the switching valve. The system according to claim 1, wherein the fluid circuit comprises a pressure sequence valve in fluid connection with the clamping actuator.
11. The system according to claim 1, wherein the fluid circuit comprises a clamp control valve that controls fluid pressure in the first line and the second line.
12. A method for securing a mechanical connection, the method comprising: activating a bypass switch to operate a pilot oil supply valve and provide fluid pressure to a switching valve; 00 actuating a counter balance valve using pressure provided through the c switching valve, whereby pressure in a main power circuit is maintained below ;an operating pressure; Sactuating a clamp control valve to cause both clamping of a clamping element and locking of a locking element; IN actuating the switching valve in response to the locking of the locking IDelement; and 0 providing the operating pressure in the main power circuit in response to 00 Sactuating the switching valve.
13. A system for securing a mechanical connection, substantially as described herein with reference to the drawings.
14. A method for securing a mechanical connection, substantially as described herein with reference to the drawings.