A support device for a lift system

Abstract

A support device 100 for a lift system having a mast (200 fig.5) and a platform (300 fig.5) has a support arm 20 for supporting the platform moveable between stowed, partially extended and fully exten

Description

The present invention relates to a support device for a lift system, such as a goods lift system. The present invention also relates to a lift system, such as a goods lift system, comprising the support device. During use of a lift or elevator, a platform rises and lowers to transport goods or people between desired levels. The lift or lift system may comprise a support device to help support the weight of the platform when the platform is at a desired level. The aim of the support device is to prevent unintended lowering of the platform when the platform is at a desired level, for example, for transporting goods onto or off of the platform, or for people to enter or exit the lift. When the load on the platform is high, some components of the lift system may be under strain such that the platform is not in alignment with a door of the lift system or a floor adjacent to the lift system. This may be a tripping hazard. In such situations, use of a support device may be particularly desirable to minimize or avoid misalignment of the platform with the door or the floor. In some known lift systems, the support device is mounted on the underside of the platform. The support device may comprise electrical components with a number of electrical cables attached to the support device. Having such a support device mounted on the underside of the platform may hinder access to the support device or other components on the underside of the platform. This may cause issues with maintenance and repair of the lift system, such as with maintenance and repair of the support device or the other components on the underside of the platform. A popular form of support device used for goods lifts is a hydraulically-activated shoot bolt, which is mounted to the underside of the lift platform. When the platform reaches the desired level, the shoot-bolt is actuated so that it extends into a recess in the lift mast. The extended shoot-bolt locks the platform in place and prevents it from lowering until the shoot-bolt is retracted. The location of these shoot-bolts under the platform means that electrical components such as hydraulic power packs, linear actuators and limit switches must be fitted to the underside of the platform. This makes maintenance difficult, and leads to unreliability, as a large number of cables must travel with the lift. It is desirable to provide a support device that ensures that the platform of a lift system is at a desired level and prevents unintended movement of the platform when the platform is at the desired level. It is also desirable to provide a support device that is simple to install and maintain. According to a first aspect of the present invention, there is provided a support device for a lift system, the lift system comprising a mast and a platform movable along the mast, the support device comprising: a support arm for supporting the platform; and a drive mechanism for moving the support arm, wherein the support arm is movable between a stowed position, a partially extended position, and a fully extended position, wherein the drive mechanism is actuatable to move the support arm from the stowed position to the partially extended position but not to the fully extended position, and wherein the support arm is movable from the partially extended position to the fully extended position when the weight of the platform is applied to the support arm. The support device may be for a goods lift system. The partially extended position is intermediate the stowed position and the fully extended position. The support arm is movable from the stowed position to the fully extended position through the partially extended position. The support arm is movable from the fully extended position to the stowed position through the partially extended position. According to a second aspect of the present invention, there is provided a lift system comprising: a mast; a platform movable along the mast; a support device according to the first aspect of the present invention mounted on the mast, wherein the support arm of the support device is configured to move from the partially extended position to the fully extended position when the platform rests on or is located on the support arm. Providing the support device of the present invention with a support arm and a drive mechanism, wherein the drive mechanism is actuatable to move the support arm from the stowed position to the partially extended position but not to the fully extended position, and wherein the support arm is movable from the partially extended position to the fully extended position when the weight of the platform is applied to the support arm, advantageously provides a mechanism to ensure, or verify, that the platform is at a desired level and height. The support device may preferably be configured to sense when the support arm is in the fully extended position. As the support arm moves to the fully extended position only when the weight of the platform is applied to it, the support device may verify that the weight of the platform has been applied to the support arm by checking whether the support arm is in the fully extended position. If the platform is not in position, the support arm will not be in the fully extended position. A mechanism to ensure, or to verify, that the platform is at a desired level and height may advantageously improve safety of the lift system. For example, the lift system may be configured so that a door of the lift system may only unlock and be openable when the support device verifies that the platform is at the desired level and height. This may prevent access to the platform or to the shaft of the lift system from a floor when the platform is not at or aligned with the floor. The platform of the lift system may only be accessible when the platform is resting on the support arm and the support arm is moved by the weight of the platform to the fully extended position. Thus, the platform of the lift system may only be accessible when the platform is at the desired level and height. The support arm and the drive mechanism may cooperate to provide a mechanism to ensure that the platform is aligned with a desired floor to avoid tripping hazards. During use of the lift system, the platform may move up the mast, past the support device having its support arm in the stowed position, and to a height slightly above a desired floor. When the platform is at a height above the desired floor, the drive mechanism of the support device may be actuated to move the support arm from the stowed position to the partially extended position, but not to the fully extended position. The platform may then be lowered onto the support arm of the support device. The weight of the platform applied to the support arm moves the support arm from the partially extended position to the fully extended position. The drive mechanism being actuatable to move the support arm from the stowed position to the partially extended position but not to the fully extended position means that the drive mechanism is limited to moving the support arm between the stowed position and the partially extended position. In other words, the drive mechanism is configured to move the support arm only between the stowed position and the partially extended position, and the drive mechanism is not configured to move the support arm beyond the partially extended position towards or to the fully extended position. Accordingly, movement of the support arm from the partially extended position to the fully extended position is possible only as a result of the weight of the platform acting on the support arm and not due to the drive mechanism driving the support arm to the fully extended position. The support arm is therefore in the fully extended position only when the platform is at the desired level and height, with its weight resting on the support arm. This provides a mechanism to verify that the platform is at the desired level and height. The support device of the present invention may be attached to or mounted on the mast of the lift system. This may advantageously reduce the number of components which need to be mounted to the platform. For example, this may advantageously reduce the quantity of electrical cabling attached to the platform and thus reduce the need for moving electrical cabling during use of the lift system. Reducing the need for moving electrical cabling may advantageously reduce the risk of damage to the cabling and to the support device. The support device being attached to the mast of the lift system may advantageously provide easy access to the support device for maintenance of the support device. For example, where the support device is attached to the mast of the lift system, maintenance may be carried out from the platform rather than from underneath the platform and inside the pit of the lift system. The support device being attached to the mast of the lift system rather than the underside of the platform may reduce the number of components on the underside of the platform to provide easy access to the components on the underside of the platform for maintenance. The support device being attachable to the mast of the lift system may enable the support device to be retrofitted onto existing lift systems without the need for replacement of the platform of the lift system. This may simplify installation of the support device into a lift system. The support device may comprise an indicator configured to indicate when the support arm is in the fully extended position. The indicator may be configured to indicate when the support arm is in the stowed position. The indicator may be a sensor, such that the support device may comprise a sensor configured to sense when the support arm is in the fully extended position. The support device may comprise another sensor configured to sense when the support arm is in the stowed position. Location monitoring switches, or location monitoring sensors, may be configured in a variety of ways to verify the position of the support arm at any given time. The support device is preferably configured to sense when the support arm is in the fully extended position, and preferably also to sense when the support arm is in the stowed position. The indicator may be configured to provide visual indication of when the support arm is in the fully extended position. The indicator may be configured to provide visual indication of when the support arm is in the stowed position. The indicator may comprise a light emitting diode (LED). The indicator may comprise a location monitoring switch. The indicator may be a location monitoring switch. The indicator may be configured to provide an electrical indication when the support arm is in the fully extended position, for example by sending an electrical signal to a device controller. The indicator may be configured to provide an electrical indication when the support arm is in the stowed position. The indicator may optionally be configured to provide an electrical indication when the support arm is in the partially-extended position. The location monitoring switch may be configured to indicate when the support arm is in the stowed position and when the support arm is in the fully extended position. The location monitoring switch may be configured to move from a first position to a second position when the support arm moves from the stowed position to the fully extended position. In other words, the location monitoring switch may be in the first position when the support arm is in the stowed position, and the location monitoring switch may be in the second position when the support arm is in the fully extended position. The location monitoring switch may be configured to provide an electrical indication when the switch moves from the first position to the second position, for example by sending an electrical signal to a device controller. The position of the location monitoring switch may provide a visual indication when the support arm is in the fully extended position and thus the platform is located on the support arm and is at the desired level or height. The location monitoring switch may be connected to the support arm of the support device. The support device may be configured such that movement of the support arm from the stowed position to the fully extended position causes movement of the location monitoring switch from the first position to the second position. The location monitoring switch may be configured to indicate when the support arm is in the partially extended position. The location monitoring switch may be located in an intermediate position between the first position and the second position when the support arm is in the partially extended position. The location monitoring switch may be configured to move to the intermediate position when the support arm is in the partially extended position. The location monitoring switch may be configured to provide three different indications when: i) the support arm is in the stowed position, ii) the support arm is in the partially extended position, and iii) the support arm is in the fully extended position. The location monitoring switch may be slidable between the first position and the second position, via the intermediate position. The location monitoring switch may protrude out of a housing of the support device. For example, the housing may comprise a slot along which a part of the location monitoring switch may protrude out of and slide along. The location monitoring switch may be configured to indicate when the drive mechanism is not actuated. For example, the location monitoring switch may be configured to indicate when the drive mechanism is not actuated and the support arm is in the stowed position. This may be the case where the support arm is biased towards the stowed position. The location monitoring switch may be configured to be in the first position when the drive mechanism is not actuated. The location monitoring switch may be configured to indicate when the drive mechanism is actuated to move the support arm to the partially extended position. The location monitoring switch may be configured to be in either the intermediate position or the second position when the drive mechanism is actuated to move the support arm to the partially extended position. The location monitoring switch may be configured to indicate when the drive mechanism is actuated to move the support arm to the partially extended position and the support arm is in the partially extended position. This may be the case when the platform is not located on the support arm to move the support arm to the fully extended position. The location monitoring switch may be configured to indicate when the drive mechanism is actuated to move the support arm to the partially extended position and the platform is not located on the support arm. In such cases, the location monitoring switch may be located in the intermediate position. The location monitoring switch may be configured to be in the intermediate position when the drive mechanism is actuated to move the support arm to the partially extended position and the support arm is in the partially extended position. The location monitoring switch may be configured to indicate when the drive mechanism is actuated to move the support arm to the partially extended position and the support arm is in the fully extended position. The location monitoring switch may be configured to indicate when the drive mechanism is actuated to move the support arm to the partially extended position but not to the fully extended position, and the support arm is in the fully extended position. This occurs when the platform is located on the support arm and it is the weight of the platform that moved the support arm from the partially extended position to the fully extended position rather than actuation of the drive mechanism that moved the support arm from the partially extended position to the fully extended position. The location monitoring switch may be configured to indicate when the drive mechanism is actuated to move the support arm to the partially extended position and the platform is located on the support arm. In such cases, the location monitoring switch may be in its second position. The location monitoring switch may be configured to be in the second position when the drive mechanism is actuated to move the support arm to the partially extended position and the support arm is in the fully extended position. The support device may comprise control electronics, for example a device controller. The location monitoring switch may be operably coupled to the control electronics. The control electronics may be located in a housing of the support device. The control electronics may be operably coupled to a power supply of the lift system. The support device may comprise a power supply, such as a battery. The power supply of the support device may be located in the housing of the support device. Alternatively the support device may be connectable to a power supply such as mains electricity. The location monitoring indicator(s) or switch(es) may preferably be configured to communicate with the control electronics to indicate the position of the support arm to the control electronics. The location monitoring switch, or the device control electronics, may be configured to generate a door lock signal when the platform is not located on the support arm of the support device. As used herein, the term “door lock signal” may also be referred to as the “first signal”. As discussed further below, the door lock signal may be received by a door lock of the lift system to lock a door of the lift system. This may prevent access to the platform or the shaft of the lift system when the platform is not at the desired floor or height. The location monitoring switch, or the device control electronics, may be configured to generate the door lock signal when the support arm is in the stowed position or in the partially extended position. The location monitoring switch, or the device control electronics, may be configured to generate the door lock signal when the support arm is not in the fully extended position. The location monitoring switch, or the device control electronics, may be configured to generate the door lock signal when the drive mechanism is not actuated to move the support arm to the partially extended position. The location monitoring switch, or the device control electronics, may be configured to generate the door lock signal when the location monitoring switch is in the first position or in the intermediate position. The location monitoring switch, or the device control electronics, may be configured to generate the door lock signal when the location monitoring switch is not in the second position. The control electronics may be configured to generate the door lock signal in the situations discussed above. In particular, the location monitoring switch may be configured to cause the control electronics to generate the door lock signal in the situations discussed above. The location monitoring switch, or the device control electronics, may be configured to generate a door unlock signal when the platform is located on the support arm of the support device. As used herein, the term “door unlock signal” may also be referred to as the “second signal”. As discussed further below, the door unlock signal may be received by a door lock of the lift system to unlock a door of the lift system. This may enable or provide access to the platform or the shaft of the lift system when the platform is at the desired floor or height. The location monitoring switch or sensor may be configured to generate the door unlock signal when the support arm is in the fully extended position, thus verifying that the platform is in position with its weight resting on the support arm. The location monitoring switch may be configured to generate the door unlock signal when the drive mechanism is actuated to move the support arm to the partially extended position and the support arm is in the fully extended position. The location monitoring switch may be configured to generate the door unlock signal when the drive mechanism is actuated to move the support arm to the partially extended position but not to the fully extended position, and the device senses that the support arm is in the fully extended position. The location monitoring switch, or the device control electronics, may be configured to generate the door unlock signal when the location monitoring switch is in the second position. The control electronics may be configured to generate the door unlock signal in the situations discussed above. In particular, the location monitoring switch may be configured to cause the control electronics to generate the door unlock signal in the situations discussed above. The support device may comprise a housing. When the support arm is in the stowed position, the support arm may be located substantially entirely within the housing. When the support arm is in the partially extended position, the support arm may protrude out of the housing. In other words, when the support arm is in the partially extended position, at least a part of the support arm may be located outside of the housing. When the support arm is in the fully extended position, the support arm may protrude out of the housing. In other words, when the support arm is in the fully extended position, at least a part of the support arm may be located outside of the housing. The support device may comprise attaching means for attaching the support device to the mast of the lift system. The support device may comprise a fixing plate for attaching or mounting the support device on the mast of the lift system. The fixing plate may comprise one or more screw holes. The fixing plate may be attached to the housing of the support device. The fixing plate may form a part of the housing. The support arm may be pivotable between the stowed position, the partially extended position and the fully extended position. The support arm may be pivotable relative to the housing or fixing plate of the support device. The support arm may be referred to as a hinged support arm. The support arm being pivotable may advantageously allow the support device to be more compact, which may make it easier to retrofit the support device into existing lift systems. In particular, the support arm being pivotable may advantageously enable the size of the support device to be reduced compared to support devices where the support arm is a shoot bolt, such as a hydraulic shoot bolt. The support arm has a support surface for supporting the platform. The support surface of the support arm is the surface of the support arm on which the platform rests, in use, when the support arm is in the fully extended position. When the platform is located on the support surface of the support arm, the support surface may be parallel to a surface on the underside of the platform. When the platform is located on the support surface, the support surface may be substantially horizontal. When the platform is located on the support surface may be substantially perpendicular to the fixing plate. When the support arm is in the fully extended position, the support surface may be substantially horizontal. When the support arm is in the fully extended position, the support surface may be substantially perpendicular to the fixing plate. When the support arm is in the stowed position, the support arm may be substantially vertical. When the support arm is in the stowed position, the support arm may be substantially parallel to the fixing plate. When the support arm is in the partially extended position, the support arm may be at angle with the fixing plate. When the support arm is in the partially extended position, the support surface of the support arm may be at an acute angle to the fixing plate. The support arm may be formed from a material with sufficient yield strength to support the platform. The support arm may be formed from a metal, such as a steel. For example, the support arm may be formed from S355 steel. Other components of the support device, such as the housing, may also be formed form a metal, such as a steel. The support arm may be formed from a material having a greater yield strength than the material forming the housing. The support device may comprise a biasing means. The biasing means may be configured to bias the support arm towards or to the stowed position. This may advantageously avoid the support arm of the support device preventing the platform from lowering when the drive mechanism is not actuated. For example, where there is a power failure and power is not being supplied to the drive mechanism, the platform may be lowered since the support arm of the support device is biased towards the stowed position. This may facilitate repair of the lift system. During use of the lift system, the platform may move up the mast, past the support device to a height above the support device, wherein the support arm of the support device is in the stowed position due to biasing of the support arm towards the stowed position. When the platform is at a height above the support device, the drive mechanism of the support device may be configured to be actuated to move the support arm from the stowed position to the partially extended position, but not to the fully extended position. The platform may then be lowered onto the support arm of the support device. The weight of the platform applied to the support arm moves the support arm from the partially extended position to the fully extended position. At this point, the platform is at the desired height for access to and from the platform, for example an operator may carry out loading and unloading of goods on the platform. When it is desired to move the platform to a different level or height, the platform may be raised such that it is no longer located on the support arm of the support device. The support arm then moves from the fully extended position to the stowed position due to biasing of the support arm towards the stowed position. Preferably the biasing means is a spring, such as a leaf spring or a coil spring. The drive mechanism of the support device may be referred to as the support device drive mechanism or support arm drive mechanism. The drive mechanism may be operably coupled to the control electronics of the support device. The drive mechanism may be configured to be turned off when the platform is located on the support arm. When the platform is located on the support arm of the support device, the control electronics may be configured to not provide power to the drive mechanism. The weight of the platform on the support arm has the effect that the support arm is held in the fully extended position without actuation of the drive mechanism. The drive mechanism may be configured to be deactivated when the support arm is in the fully extended position. When the support arm is in the fully extended position, the control electronics may be configured to not provide power to the drive mechanism. The drive mechanism may be configured to be deactivated when the location monitoring switch is in the second position. When the location monitoring switch is in the second position, the control electronics may be configured to not provide power to the drive mechanism. The drive mechanism may be configured to be deactivated when the support device generates a door unlock signal. When the support device generates a door lock signal, the control electronics may be configured to not provide power to the drive mechanism. In a preferred embodiment, the drive mechanism may comprise a solenoid. The drive mechanism of the support device may be configured to move the support arm of the support device from the stowed position to the partially extended position when the platform is located above the support arm. The drive mechanism of the support device may be configured to move the support arm of the support device from the stowed position towards the partially extended position when the platform is located at least 20 millimetres, at least 50 millimetres, or at least 100 millimetres above the support arm. The lift system may comprise one or more platform height sensors for detecting the location of the platform relative to the support device, in particular relative to the support arm of the support device. The one or more platform height sensors may be mounted on the mast or on the platform. The platform height sensors may be a component of the support device. In other words, the support device may comprise the platform height sensors. The platform height sensor may be operably coupled to the control electronics of the support device. The platform height sensor(s) may be operably coupled to the drive mechanism of the support device. The platform height sensor(s) may be configured to generate a clearance signal when the platform is located above the support device or the support arm, such as at least 20 millimetres, at least 50 millimetres, or at least 100 millimetres above the support device or support arm. The drive mechanism may be configured to be activated when the platform height sensor generates the clearance signal. The drive mechanism of the support device may be configured to move the support arm of the support device from the stowed position to the partially extended position when the sensor generates the clearance signal. The drive mechanism may be configured to receive the clearance signal from the platform height sensor. The drive mechanism of the support device may be configured to be activated to move the support arm of the support device from the stowed position to the partially extended position when the drive mechanism receives the clearance signal. The platform height sensor may for example be an infrared sensor or limit switch. The lift system may comprise a cage. The cage may be referred to as a cage tower. The platform of the lift system may move along a shaft defined by the cage. Accordingly, the platform may be located within the cage. The platform may comprise a ledge. The ledge of the platform may be configured to interact with the support arm of the support device. The ledge of the platform may be configured to apply weight to the support arm of the support device. When the platform is at the desired height or level, the ledge of the platform may be located on the support arm of the support device to apply the weight of the platform to the support device to move the support arm to the fully extended position. The cage of the lift system may comprise the mast. The mast may form a part of the cage. The mast may be located on one wall of the cage of the lift system. The mast may be considered a frame on a wall of the cage. The lift system may comprise one or more masts. The lift system may comprise a plurality of masts. For example, the lift system may comprise two or four masts. The lift system may comprise a door for providing access to or for accessing the platform. The cage of the lift system may comprise the door. The door may form a part of the cage. The lift system may be configured such that the door is locked and prevented from opening when the support arm is in the stowed position or in the partially extended position. This is such that the door is prevented from opening when the platform is not resting on the support arm of the support device and therefore the platform is not at the desired level or height. The lift system may be configured such that the door is unlocked and free to open when the support arm is in the fully extended position. This is such that the door may be opened to allow access to the platform when the platform is resting on the support arm of the support device and the platform is therefore at the desired level or height. The lift system may comprise a door locking mechanism or door lock for locking the door. The door lock may be a component of the door. In other words, the door may comprise the door lock. The door lock may be operably coupled to the support device. The door lock may be operably coupled to the support device to receive one or more signals generated by the support device. The door lock may be configured to receive one or more signals generated by the support device, such as by the location monitoring switch. The door lock may be operably coupled to the support device to receive a door lock and a door unlock signal generated by the support device. The door lock may be operably coupled to the location monitoring switch of the support device and configured to receive one or more signals generated by the location monitoring switch. The door lock may be configured to lock the door when the support arm is in the stowed position or in the partially extended position. In other words, the door lock may be configured to prevent the door from opening when the door locking mechanism receives a door lock signal generated by the support device when the support arm is in the stowed position or in the partially extended position. The door lock may be configured to unlock the door when the support arm is in the fully extended position. The door lock may be configured to unlock the door when the door locking mechanism receives a door unlock signal generated by the support device when the support arm is in the fully extended position. In other words, the door lock may be configured to allow the door to open when the door locking mechanism receives a door unlock signal generated by the support device when the support arm is in the fully extended position. The door lock may be configured to lock the door and therefore prevent the door from opening when there is a power failure. For example, the door lock may be configured to prevent the door from opening when no power is being supplied to the door lock. The door lock may be configured to prevent the door from opening when no signal is being received by the door lock. The door lock may be configured to prevent the door from opening when the support device is not generating a signal, including the door lock and the door unlock signal. The lift system may comprise one or more doors. The lift system may comprise a plurality of doors. The plurality of doors may be arranged along the height of the cage. The lift system may comprise one door per desired level or floor. Each door may comprise a corresponding door lock having the features discussed above. The lift system may comprise one or more support devices according to the first aspect of the invention. The lift system may comprise a plurality of support devices. The support devices may be arranged along the height of the lift system, such as along the height of the cage of the lift system. The lift system may comprise at least one support device at set heights along the height of the lift system. The lift system may comprise at least one support device per floor. For example, where the lift system is for transporting goods between two levels, the lift system may comprise at least one support device for supporting the platform at the first level and at least one support device for supporting the platform at the second level. Each support device may be operably coupled to a door lock of the lift system. Each support device may be operably coupled to a corresponding door lock of the lift system. The location monitoring switch of each support device may be operably coupled to a door lock of the lift system. The location monitoring switch of each support device may be operably coupled to a corresponding door lock of the lift system. The lift system may comprise one or more support devices mounted to each mast of the lift system. The lift system may comprise a plurality of support devices mounted to each mast of the lift system. For example, the lift system may comprise a plurality of support devices, wherein two support devices are mounted to each mast of the lift system. Instead of the support device being mounted to the mast of the lift system, the support device may be mounted to the platform. For example, the support device may be mounted to the underside of the platform. When the platform is at a desired level, the support arm of the support device may be located on a part of the mast, such as a ledge of the mast. The interaction between the support arm and the mast may be such that the weight of the platform is applied to the support arm of the support device to move the support arm to the fully extended position. Mounting the support device to the platform may minimise the number of support devices required by the lift system. The lift system may comprise a platform drive mechanism. The platform drive mechanism may be configured to drive the platform from below a support device to above the support device or support arm of the support device and then to lower the platform such that the platform rests on the support arm of the support device. The platform resting on the support arm moves the support arm to the fully extended position. The platform drive mechanism may be configured to drive the platform from below the support device to a location above the support device that is less than or equal to 200 millimetres, or less than or equal to 150 millimetres, or less than or equal to 100 millimetres above the support device prior to lowering the platform such that the platform rests on the support arm of the support device. The platform drive mechanism may be configured to drive the platform from below the support device to a location above the support arm of the support device that is less than or equal to 200 millimetres, or less than or equal to 150 millimetres, or less than or equal to 100 millimetres above the support arm prior to lowering the platform such that the platform rests on the support arm. The lift system may comprise a hydraulic cylinder configured to drive movement of the platform. The hydraulic cylinder may be mounted on the mast. The lift system may comprise a leaf chain connecting the hydraulic cylinder to the platform. The platform drive mechanism may comprise the hydraulic cylinder and the leaf chain. When the support arm of the support device is in the fully extended position, the hydraulic cylinder may have a non-zero pressure. When the support arm of the support device is in the fully extended position, the hydraulic cylinder may have a residual pressure. This may be such that some hydraulic pressure remains in the hydraulic cylinder when the platform is located on and supported by the support arm of the support device. This may advantageously avoid the leaf chain from going slack. The lift system may comprise a check valve. The check valve may be configured to retain pressure in the hydraulic system when at least one of: the platform is located on the support arm of the support device; the support arm of the support device is in the fully extended position; the location monitoring switch is in the second position; the support device generates a door unlock signal; and the door lock receives a door unlock signal or is unlocked. The present invention will be further described, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a schematic perspective view of a support device according to the first aspect of the present invention having a support arm in a stowed position; Figure 2A shows a schematic side view of the support device shown in Figure 1 with the support arm in a partially extended position; Figure 2B shows a schematic side sectional view of the support device as shown in Figure 2A; Figure 2C shows a schematic side perspective view of the support device as shown in Figure 2A; Figure 3A shows a schematic side view of the support device shown in figure 1 with the support arm in a fully extended position; Figure 3B shows a schematic side sectional view of the support device as shown in Figure 3A; Figure 3C shows a schematic side perspective view of the support device as shown in Figure 3A; Figure 4 shows a schematic perspective view of a portion of a lift system according to the second aspect of the present invention comprising the support device shown in Figures 1, 2A to 2C and 3A to 3C mounted to a mast of the lift system; and Figure 5 shows a schematic perspective view of a portion of the lift system shown in figure 4 with a platform of the lift system resting on the support arm of the support device. Figures 1, 2A to 2C, and 3A to 3C shows a support device 100 in accordance with the first aspect of the present invention. The support device 100 is for use with a lift system comprising a mast and a platform movable along the mast. The support device 100 comprises a housing 10, a support arm 20 for supporting the platform, a drive mechanism 30 for moving the support arm 20, a location monitoring switch 40 and a fixing plate 50 for mounting the support device on the mast. The support arm 20 comprises a support surface 22 on which the platform is configured to rest on. As shown in Figures 2B and 3B, the drive mechanism 30 comprises a solenoid 32 as shown in Figures 2B and 3B. As shown in Figures 2C and 3C, the fixing plate 50 comprises one or more screw holes 52 through which screws may be inserted for attaching the support device to the mast of the lift system. The support arm 20 is pivotable between a stowed position (as shown in Figure 1), a partially extended position (as shown in Figures 2A to 2C), and a fully extended position (as shown in Figures 3A to 3C). As shown in Figure 1, when the support arm 20 is in the stowed position, the support arm 20 is substantially parallel to the fixing plate 50. As shown in Figures 2A to 2C, when the support arm 20 is in the partially extended position, the support arm 20 is at an angle to the fixing plate 50, and the support surface 22 of the support arm 20 is at an acute angle with the fixing plate 50. As shown in Figures 3A to 3C, when the support arm 20 is in the fully extended position, the support arm 20 is at an angle to the fixing plate 50, and the support surface 22 of the support arm 20 is substantially perpendicular to the fixing plate 50. The drive mechanism 30 is actuatable to move the support arm 20 from the stowed position to the partially extended position but not to the fully extended position. The support device 100 comprises a biasing means to bias the support arm 20 to the stowed position. During use of the support device 100 with a lift system, the platform of the lift system is raised by a platform drive mechanism to a location above the support arm 20. As the platform passes the support arm 20, the support arm 20 is in the stowed position due to the biasing means. When a platform height sensor (not shown) senses that the platform is at a location above the support arm 20, the drive mechanism 30 is configured to be actuated to move the support arm 20 to the partially extended position. The drive mechanism 30 is limited to moving the support arm 20 to the partially extended position, and is not capable of driving the support arm 20 to the fully extended position. The platform is then lowered onto the support arm 20. The weight of the platform on the support arm 20 moves the support arm 20 from the partially extended position to the fully extended position. The location monitoring switch 40 is configured to indicate when the support arm 20 is in the stowed position, the partially extended position and the fully extended position. When the support arm 20 is in the stowed position, the location monitoring switch 40 is in a first position, as shown in Figure 1. When the drive mechanism 30 is actuated to move the support arm 20 from the stowed position to the partially extended position, and the platform is not resting on the support arm 20, the support arm 20 is in the partially extended position. When the support arm 20 is in the partially extended position, the location monitoring switch 40 is in an intermediate position, as shown in Figures 2A to 2C. When the platform is lowered to be resting on the support arm 20, the support arm 20 is moved under the weight of the platform from the partially extended position to the fully extended position. Accordingly, when the support arm 20 is in the fully extended position, the platform is at a desired level or floor. When the support arm 20 is in the fully extended position, the location monitoring switch 40 is in the second position as shown in Figures 3A to 3C. The location monitoring switch 40 is configured to generate a door lock signal when the support arm 20 is not in the fully extended position, such as when the support arm 20 is in the stowed position or the partially extended position. The location monitoring switch 40 is configured to generate a door unlock signal when the support arm 20 is in the fully extended position. A door lock of a door of the lift system may be configured to receive the signals generated by the location monitoring switch 40 and lock and unlock the door accordingly. Figure 4 shows the support device 100 shown in Figures 1, 2A to 2C, and 3A to 3C mounted onto a mast 200 of a lift system via the fixing plate 50 and screws. The support device 100 may be mounted on the mast of the lift system such that when the platform is on the support arm 20 of the support device 100 and the support arm 20 is in the fully extended position, the platform is at a desired level and height. Figure 5 shows a platform 300 of the lift system resting on the support arm 20 of the support device 100. The platform 300 comprises a ledge 310 that is configured to interact with the support arm 20. In particular, when the platform 300 is lowered onto the support arm 20 of the support device 100, the ledge 310 of the platform 300 rests on the support arm 20 to apply the weight of the platform 300 onto the support arm 20 to move the support arm 20 into the fully extended position. 5 The specific embodiments and examples described above illustrate, but do not limit, the invention. It is to be understood that other embodiments of the invention may be made and the specific embodiments and examples described herein are not exhaustive.

Claims

1. A support device for a lift system comprising a mast and a platform movable along the mast, the support device comprising:a support arm for supporting the platform; anda drive mechanism for moving the support arm,wherein the support arm is movable between a stowed position, a partially extended position and a fully extended position,wherein the drive mechanism is actuatable to move the support arm from the stowed position to the partially extended position but not to the fully extended position, andwherein the support arm is movable from the partially extended position to the fully extended position when the weight of the platform is applied to the support arm.

2. A support device according to claim 1 comprising an indicator configured to indicate when the support arm is in the fully extended position.

3. A support device according to claim 1 or 2 comprising a location monitoring switch configured to indicate when the support arm is in the stowed position and when the support arm is in the fully extended position.

4. A support device according to claim 3, wherein the location monitoring switch is configured to indicate when the drive mechanism is not actuated.

5. A support device according to claim 3 or 4, wherein the location monitoring switch is configured to indicate when the drive mechanism is actuated to move the support arm to the partially extended position.

6. A support device according to any one of claims 3 to 5, wherein the location monitoring switch is configured to indicate when the drive mechanism is actuated to move the support arm to the partially extended position and the support arm is in the fully extended position.

7. A support device according to any one of claims 3 to 6, wherein the location monitoring switch is configured to move from a first position to a second position when the support arm moves from the stowed position to the fully extended position.

8. A support device according to claim 7, wherein the location monitoring switch is configured to be in the second position when the drive mechanism is actuated to move the support arm tothe partially extended position but not to the fully extended position, and the support arm is in the fully extended position.

9. A support device according to claim 7 or 8, wherein the location monitoring switch is configured to be in an intermediate position between the first position and the second position when the drive mechanism is actuated to move the support arm to the partially extended position and the support arm is in the partially extended position.

10. A support device according to claim 9, wherein the location monitoring switch is configured to generate a door lock signal when the location monitoring switch is in the first position or when the location monitoring switch is in the intermediate position.

11. A support device according to claim 9 or 10, wherein the location monitoring switch is configured to generate a door unlock signal when the location monitoring switch is in the second position.

12. A support device according to any one of claims 3 to 11, wherein the location monitoring switch is configured to generate a door lock signal when the support arm is in the stowed position or when the support arm is in the partially extended position.

13. A support device according to any one of claims 3 to 12, wherein the location monitoring switch is configured to generate a door lock signal when the drive mechanism is not actuated to move the support arm to the partially extended position.

14. A support device according to any one of claims 3 to 13, wherein the location monitoring switch is configured to generate a door unlock signal when the support arm is in the fully extended position.

15. A support device according to any one of claims 3 to 14, wherein the location monitoring switch is configured to generate a door unlock signal when the drive mechanism is actuated to move the support arm to the partially extended position but not to the fully extended position, and the support arm is in the fully extended position.

16. A support device according to any one of the preceding claims comprising a fixing plate for mounting the support device on the mast of the lift system.

17. A support device according to any one of the preceding claims, wherein the support arm is pivotable between the stowed position, the partially extended position and the fully extended position.

18. A support device according to any one of the preceding claims comprising a biasing means configured to bias the support arm towards the stowed position.

19. A support device according to any one of the preceding claims comprising a platform height sensor for detecting the location of the platform relative to the support device, wherein the platform height sensor is configured to generate a clearance signal when the platform is located above the support arm of the support device, and wherein the drive mechanism is configured to move the support arm of the support device from the stowed position to the partially extended position when the platform height sensor generates the clearance signal.

20. A lift system comprising:a mast;a platform moveable along the mast;a support device according to any preceding claim mounted on the mast, wherein the support arm of the support device is configured to move from the partially extended position to the fully extended position when the platform rests on the support arm.

21. A lift system according to claim 20 comprising a door for accessing the platform and a door lock for locking the door, wherein the door lock is configured to lock the door when the support arm is in the stowed position or in the partially extended position, and wherein the door lock is configured to unlock the door when the support arm is in the fully extended position.

22. A lift system according to claim 21, wherein the support device comprises a location monitoring switch, wherein the door lock is configured to receive one or more signals generated by the location monitoring switch, wherein the location monitoring switch is configured to generate a door unlock signal when the support arm is in the fully extended position, and wherein the door lock is configured to unlock the door when the door lock receives the door unlock signal.

23. A lift system according to claim 22, wherein the location monitoring switch is configured to generate a door lock signal when the support arm is in the stowed position or in the partially extended position, and wherein the door lock is configured to lock the door when the door lock receives the door lock signal.

24. A lift system according to any one of claims 20 to 23, wherein the drive mechanism of the support device is configured to move the support arm of the support device form the stowed position to the partially extended position when the platform is located above the support arm.5 25. A lift system according to any one of claims 20 to 24 comprising a platform drivemechanism configured to drive the platform from below the support device to a location above the support device prior to lowering the support device onto the support arm of the support device.

Images