AU2014200762A1 - Lock assembly for a hoist - Google Patents

Abstract

H:\cab\Interwoven\NRPortbI\DCC\CAB\60204011.doc- 13/02/2014 A lock assembly for a hoist used to service levels of a building, the assembly including a lock device for locking an access gate on one of the levels of the building and a mechanical switch coupled to the device, the switch being actuated when the hoist is positioned at a fixed location relative to the level, in order to trigger the lock device to release the gate and allow loading and unloading of the hoist.

Description

H:\cab\Interwoven\NRPortbl\DCC\CAB\60204011.doc- 13/02/2014 LOCK ASSEMBLY FOR A HOIST FIELD OF THE INVENTION [0001] The present invention relates to a lock assembly for a hoist. BACKGROUND OF THE INVENTION [0002] A scaffold hoist is used to service various levels of a building under construction. The hoist is raised and lowered up an outside of the building on dedicated framework, to transport personnel, equipment and materials to the levels. Each level will generally have a gate that is opened, when required, to allow loading and unloading of the hoist. [0003] For safety, an automatic locking system is used to lock the gate in the closed condition until it needs to be opened. The locking mechanism includes a laser device mounted on the hoist and a reflective panel mounted at each level. When the hoist is stopped at one of the levels, an optical circuit is established by a laser beam emitted from the device being reflected back to a sensor of the device. An electrical solenoid is then activated to release a lock to allow the gate to be opened. [0004] When the hoist moves to a different floor, the optical circuit is broken and the gate is returned to a locked condition. A problem with that arrangement is that the reflector panel needs to be accurately positioned and any misalignment can result in the optical circuit being broken and the gate being locked, even when the hoist is correctly positioned. Misalignment can be caused either by a direct knock to the reflective panel or simply through operational vibration transmitted through the structure of the building or adjacent scaffolding. OBJECT OF THE INVENTION [0005] The present invention seeks to provide an alternative to the above locking system.

H:\cab\Interwoven\NRPortbl\DCC\CAB\60204011.doc- 13/02/2014 -2 SUMMARY OF THE INVENTION [0006] In accordance with the invention, there is provided a lock assembly for a hoist used to service levels of a building, the assembly including a lock device for locking an access gate on one of the levels of the building and a mechanical switch coupled to the device, the switch being actuated when the hoist is at a specific location relative to the level, in order to trigger the lock device to release the gate and allow loading and unloading of the hoist. [0007] Preferably, the switch is mounted to a hoist frame that is positioned adjacent scaffolding installed around the building and the assembly further includes a mechanical link to the lock device. [0008] Preferably, the mechanical link is a cable. [0009] Alternatively, the switch is coupled to the lock device via an electrical circuit and the lock device includes a solenoid with a plunger that moves between a locked and unlocked position. [0010] Preferably, the switch includes a pivotal arm that rocks between a free first position and an engaged second position when the hoist is present at the level. [0011] Preferably, the arm includes a roller adapted to engage a vertical rail on the hoist, the rail being formed as a double ended ramp whereby the roller moves along one end of the ramp, into the engaged second position, when the hoist is at the level and moves back along the other end of the ramp, into the free first position, after the hoist leaves the level. [0012] Preferably, the arm is biased into the free position. [0013] Preferably, the arm has a guide roller to maintain positioning of the arm relative to the rail. [0014] In another aspect, there is provided a hoist system with a hoist to service levels of a building and a lock assembly, as described above, to lock a gate on one of H:\cab\Interwoven\NRPortbl\DCC\CAB\60204011.doc- 13/02/2014 -3 the levels of the building. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The invention has been described, by way of non-limiting example only, with reference to the following drawings, in which: Figure 1 is a perspective view of a test rig with a hoist, scaffolding and a gate; Figure 2 is a perspective view of the gate and lock; Figure 3 is a perspective view of a mechanical switch with a pivotal arm is a first position; Figure 4 is a perspective view of the arm in an engaged second position as the hoist is lowered; and Figure 5 is a perspective view of the arm returned to the first position as the hoist moves past the mechanical switch. DETAILED DESCRIPTION OF THE INVENTION [0016] Referring firstly to Figure 1, a test rig 1 is shown as including a hoist 2 arranged to travel up and down a hoist frame 3, located adjacent scaffolding 4 that is installed around a building 5. The hoist is shown next to a gate 6 that provides access to a level 7 of the building 5. [0017] A lock assembly 8 is also shown as including a mechanical switch 9 mounted on the frame 3. The switch 9 is connected to a mechanical link in the form of a cable 10 that is coupled to a lock device 11, as shown in Figure 2. [0018] Referring now to Figure 2, the lock device 11 includes a housing 13 fitted to an inside of the gate 6 and a bracket 14 to which a tail end 15 of the cable 10 is connected.

H:\cab\Interwoven\NRPortbl\DCC\CAB\60204011.doc- 13/02/2014 -4 [0019] The housing 13 carries a piston 16 arranged to slide internally of the housing 13 from an extended position shown to a retracted position. Movement of the piston 16 is controlled by the cable, in response to movement of the mechanical switch. [0020] When the piston 16 is in the extended position, a slide bolt 17 is obstructed from sliding movement to the left, as shown. This prevents the slide bolt 17 from being released and that serves to lock the gate 6 closed. [0021] When the piston is raised, the bolt 17 is free to slide open and thereby allow the gate 6 to be opened to provide access between the level 7 and the hoist 2. [0022] Turning now to Figure 3, the mechanical switch 9 is shown in more detail as including a pivotal arm 18 connected to the frame 3 by a bolt 19. The arm has a roller 20 at one end 21, with a second guide roller 22. An eyelet 23 is provided at the other end 24 of the arm 18 to connect with an attachment 25 of the cable. [0023] In the position shown, the arm is in a free first position, pivoted clockwise, indicating the hoist 3 is not in a position suitable for the gate to be opened. As such, the piston 16 of the lock device 11, which is coupled to the switch 9 via the cable 10, is in an extended condition whereby to keep the gate 6 locked. [0024] As the hoist 3 is lowered to a position adjacent the level 7, the roller 20 of the arm 18 engages a vertical rail 26 fitted to the hoist 3. The rail 26 is vertically arranged and includes ramp sections 27, 28 (seen in Figure 4) and a straight rail section 29. [0025] The engagement of the roller 20 with the rail sections 27, 29 forces the arm to pivot in an anti-clockwise direction, which forces the attachment 25 downwardly to pull on the cable 10. The movement of the cable 10 is transmitted to the lock device 11, which causes the piston 18 to be lifted, thereby unlocking the slide bolt 17 to allow the gate 6 to be opened. [0026] When the roller 20 first engages with the rail 26, relative forces between the roller 20 and rail 26 may initially cause the roller to pivot in the incorrect, clockwise direction. The guide roller 21 then operates as a secondary roller to engage the ramp H:\cab\Interwoven\NRPortbl\DCC\CAB\60204011.doc- 13/02/2014 -5 section 27 and ensure the arm travels in the correct direction, thereby maintaining correct alignment between the arm 18 and the rail 26 and avoiding the arm 18 jamming up against the rail 26. [0027] When the arm 18 and rail 26 are positioned as shown in Figure 4, the mechanical switch 9 is in a position to indicate the hoist 3 is at the correct position relative to the level 7 to allow the gate to be opened and personnel and equipment to be loaded on and off the hoist 3. [0028] After the loading or unloading operation is complete, the gate 6 is again closed and the hoist 3 is operated to move to a different level, down the frame 3, which causes the rail 26 to be lowered relative to the mechanical switch 9. This results in the roller 20 travelling down the return ramp section 28 and that causes the arm 24 to rotate clockwise, back to its original position, in which the piston 16 of the lock device 11 locks the gate 6 closed. [0029] To maintain the locked condition of the overall lock assembly 8, the arm 18 is preferably mechanically biased into the locked position. Alternatively, the lock device 11 itself includes the biasing element. [0030] As a further alternative, various mechanical components of the lock assembly 8 may be replaced with electrical components. For example, an electrical circuit with a solenoid plunger may be used instead of the mechanical link of the connecting cable 10 and the associated lock device 11. [0031] This invention has been described by way to a single hoist 3 on a test rig 1. However, it will be appreciated the invention also relates to an entire hoist system installed on a building, with one or more hoists arranged to service various levels of the building and one or more associated lock assemblies to lock respective gates on each of the levels of the system. [0032] Many other variations and modifications may be made to the invention without departing from the spirit and scope of the invention described.

H:\cab\Interwoven\NRPortbl\DCC\CAB\60204011.doc- 13/02/2014 -6 LIST OF PARTS 1. Test rig 2. Hoist 3. Frame 4. Scaffolding 5. Building 6. Gate 7. Level 8. Lock assembly 9. Mechanical switch 10. Cable 11. Lock Device 12. 13. Housing 14. Bracket 15. End 16. Piston 17. Slide bolt 18. Arm 19. Bolt 20. Roller 21. End 22. Guide roller 23. Eyelet 24. End 25. Attachment 26. Rail 27. Ramp section 28. Ramp section 29. Straight section

Claims (9)

1. A lock assembly for a hoist used to service levels of a building, the assembly including a lock device for locking an access gate on one of the levels of the building and a mechanical switch coupled to the device, the switch being actuated when the hoist is positioned at a fixed location relative to the level, in order to trigger the lock device to release the gate and allow loading and unloading of the hoist.

2. The lock assembly of claim 1, wherein the switch is mounted to a hoist frame positioned adjacent scaffolding installed around the building and the assembly further includes a mechanical link to the lock device.

3. The lock assembly of claim 2, wherein the mechanical link is a cable.

4. The lock assembly of claim 1, wherein the switch is coupled to the lock device via an electrical circuit and the lock device includes a solenoid with a plunger that moves between a locked and unlocked position.

5. The lock assembly of claim 1, wherein the switch includes a pivotal arm that rocks between a free first position and an engaged second position when the hoist is present at the level.

6. The lock assembly of claim 5, wherein the arm includes a roller adapted to engage a vertical rail on the hoist, the rail being formed as a double ended ramp whereby the roller moves along one end of the ramp, into the engaged position, when the hoist is at the level and moves back along the other end of the ramp, into the free position, after the hoist leaves the level.

7. The lock assembly of claim 6, wherein the arm is biased into the free position.

8. The lock assembly of claim 6, wherein the arm has a guide roller to maintain positioning of the arm relative to the rail.

9. A hoist system with a hoist to service levels of a building and the lock assembly of any one of claims 1 to 8, to lock a gate on one of the levels.