GB2523405A

GB2523405A - Actuated barrier

Info

Publication number: GB2523405A
Application number: GB1403288.2A
Authority: GB
Inventors: Simon Robert Martin
Original assignee: NEWGATE NEWARK Ltd
Current assignee: NEWGATE NEWARK Ltd
Priority date: 2014-02-25
Filing date: 2014-02-25
Publication date: 2015-08-26
Anticipated expiration: 2034-02-25
Also published as: GB2523405B; GB201403288D0

Abstract

A boom actuation system for an access barrier comprises electric drive system 30 which includes a gearbox (54, Fig.5) via which output torque from an electric motor (52, Fig.5) is transferred to a boom (28, Fig.2). The drive system is mounted on a chassis which may comprise bulkhead 34, cross-members (36, Fig.4) and vertical supports (38, Fig.4). A manual drive system may also be mounted on the chassis allowing the boom to be raised via a handle (42, Fig.4). The chassis and drive systems can be inserted into and removed from housing 10 for replacement or maintenance. The drive systems may be on opposite sides of the bulkhead accessed via different doors (20, Fig.1). Alternatively output torque from a boom actuation motor is transferred via a gearbox to a shaft passing there-through with one end connectable to a boom and the other end comprising a mounting for an angular orientation member.

Description

TITLE OF THE INVENTION

Actuated Barrier

BACKGROUND OF THE INVENTION

The present invention relates to actuable access barriers and more particularly, although not exclusively, to actuable barriers that can be raised or lowered to selectively control vehicular access, for example at a site entrance or a crossing.

At a crossing between a railway line and a road, it is common to provide a barrier system in order to avoid the possibility of road traffic crossing the railway line when a train is approaching. The barrier can thus be raised and lowered by an actuator triggered by a control signal. Similar types of barrier are used to control access to and/or from sites by vehicles.

Conventional barriers have historically been actuated hydraulically. An example of an electrohydraulic barrier actuation system is described in EP03331 84.

Barriers need to be replaced after a predetermined life in service or else in response to one or more faults. Conventional hydraulic actuation mechanisms are beneficial in that they can offer some natural hydraulic damping of the barrier operation in use. However such actuators are relatively complicated and time-consuming to replace due, at least in part, to the need to connect a new hydraulic system. Furthermore hydraulic systems offer a number of failure modes due to, for example, fluid leaks and resulting loss of hydraulic pressure.

Upon failure of a hydraulic system, there exists a need to be able to actuate the barrier by another means. However a direct connection with a hydraulic actuator hampers the ability to provide a simple back-up actuation mechanism.

The replacement of conventional hydraulic actuators offers an opportunity to improve upon existing product specification. However any such modification of existing designs is restricted by the need for the new actuation system to be compliant with existing barrier housing geometry amongst other operational constraints.

It is an aim of the present invention to provide a barrier which overcomes or mitigates one or more of the above problems. It may be considered an additional or alternative aim to provide a replacement rail barrier actuation system which offers a simplified installation and/or replacement procedure.

BRIEF SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided an access barrier comprising a housing, a boom depending from the housing, the boom being pivotably mounted to allow the selective raising and lowering of the boom in use, and a boom actuation system comprising an electric motor and gearbox arranged such that an output torque from the motor is transferred to the boom via the gearbox, wherein the boom actuation system is mounted to a common support frame, the common support frame being removably insertable into the housing to allow installation and replacement of the boom actuation system.

The common support frame may comprise a chassis or carriage. The support frame may comprise a plurality of upright support members and one or more cross members extending between said upright support members. The frame may comprise a plurality of mounting points for components of the boom actuation system. The boom actuation system and chassis may comprise a common assembly which may beneficially be manipulated and transported by the chassis.

The support frame may be slidably insertable into the housing, for example into an open end or face of the housing. The support frame may be insertable into the housing from above. The housing may comprise an elongate slot, for example in a side wall thereof, which opens at the end of the housing to receive the boom actuation shaft. The support frame and housing may be generally rectangular in plan or otherwise correspondingly shaped.

The housing may have a plurality of closures or doors. A closure may be provided on opposing sides of the housing.

The barrier may or may not be a railway barrier. The barrier may be a heavy-duty barrier.

The boom may be mounted to a shaft, which may be arranged for rotation relative to the gearbox in use. The shaft may or may not pass through the gearbox. The gearbox may or may not provide a direct drive arrangement with respect to the shaft.

The boom actuation system may comprise a manual boom actuation mechanism.

The manual actuation mechanism may comprise a drive member arranged for engagement with the shaft. The shaft may comprise a common shaft for both the manual actuation mechanism and the electrical actuation arrangement.

The manual actuation mechanism may be selectively engageable with the barrier/shaft. Thus the manual actuation mechanism may be connected in the force path with the shaft when the electrical motor or gearbox fails. Alternatively, the manual actuation mechanism may be passively connected with the shaft in normal use but engageable to drive the shaft in a backup mode of use. The manual actuation mechanism may provide a manual override mechanism.

The shaft may comprise an arm depending outwardly from the axis of rotation for actuation by the manual actuation mechanism.

The manual actuation mechanism may be mounted to the support frame. The support frame may comprise a wall or cross member. The manual actuation mechanism may be mounted on an opposing side of the wall to the electric motor and/or gearbox. The wall may be a dividing wall. Thus an operator may safely operate the manual mechanism from an opposing side of the housing to that of the electric motor.

The manual actuation mechanism may comprise a handle. The manual actuation mechanism may comprise a toothed member such as a gear or rack. A rack and pinion mechanism may be used. Alternatively, the manual actuation mechanism may comprise a fluid pressure (e.g. hydraulic) actuator, such as a piston in cylinder arrangement. A fluid pressure mechanism, may advantageously comprise a valve to allow selective actuation of the boom under fluid pressure.

The boom actuation system may comprise a control unit, which may be mounted to the support frame.

The boom actuation system may comprise one or more rotation or angular orientation sensors, typically for determining the angular orientation of the shaft.

The shaft may comprise one or more radially extending member for use in determining the shaft angular orientation. A plurality of such radial members may be provided which may be arranged along the axis of the shaft. The radial members may be angularly offset about the shaft axis. One or more sensor may detect the presence of the, or each, radial member at a predetermined angular orientation. The shaft may comprise a plurality of limit switches.

A controller may vary the speed of rotation of the boom between raised and lowered conditions. The speed may be varied according to the angular position of the boom/shaft. The speed of rotation may be decreased from a predetermined angular orientation to either the raised or lowered position.

According to a second aspect of the invention, there is provided a method of installing an access barrier comprising: providing a boom actuation system including an electric motor and a gearbox, the gearbox being operably mounted to a shaft for driving the boom in use; mounting the boom actuation system to a common support frame; and inserting the support frame with the boom actuation system mounted thereon into a housing at the site of the access barrier.

The method typically involves attaching the boom to the shaft once the support frame has been inserted into the housing. The boom actuation system may be electrically connected to a connector within the housing.

According to a third aspect of the invention, there is provided a boom actuation system for use in the first aspect.

According to a fourth aspect, there is provided a boom actuation system for an access barrier comprising an electric motor and gearbox arranged such that an output torque from the motor is transferred via the gearbox to a shaft passing through the gearbox, wherein the shaft has a first portion extending from a first side of the gearbox for connection to a boom in use and a second portion extending from a second side of the gearbox, the second portion of the shaft comprising a mounting for one or more of a shaft angular orientation indicator and/or a manual shaft actuation link member.

The second portion may comprise one or more radial member or arm. The second member may comprise a plurality of radial members or arms at spaced locations along the shaft axis.

Wherever practicable, any of the essential or preferable features defined in relation to any one aspect of the invention may be applied to any further aspect.

Accordingly the invention may comprise various alternative configurations of the features defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

Practicable embodiments of the invention are described in further detail below by way of example only with reference to the accompanying drawings, of which: Fig. 1 shows a side view of a housing for use in accordance with the present invention; Figure 2 shows an above view of the housing of Figure 1; Figure 3 shows a front view of the housing of Figure 1 with a boom actuation system therein according to one example of the invention; Figure 4 shows a rear view of the housing of Figure 3; Figure 5 shows a three-dimensional view of a boom actuation system according to an example of the invention prior to insertion into the housing; Figure 6 shows a front view of the actuation system of Figure 5; Figures 7A and 7B show different angular orientations of a shaft assembly for the boom actuation system in raised and lowered conditions; Figure 8 shows an example of a radial orientation indicator for mounting on the shaft; Figure 9 shows a three-dimensional view of a boom actuation system according to a further example of the invention; Figure 10 shows a side view of a barrier mounting according to one example of the invention; and, Figure 11 shows a rear view of a further example of a manual boom actuation mechanism.

DETAILED DESCRIPTION OF THE INVENTION

Turning firstly to Figures 1 and 2, there is shown a housing 10 comprising upstanding side walls 12, 14 spaced by front and rear faces 16, 18. The front and rear faces 16, 18 each comprise a hinged closure 20 such that those walls are openable to allow access into the housing interior. The housing typically has a base panel, i.e. to provide a complete enclosure, although this may not be essential in other embodiments. An upper surface 22 of the housing 10 is provided by a lid 22, which is sloped/profiled to promote water runoff.

The majority of the front 16 and rear 18 faces is provided by respective closures in this example such that the closures each have a surface area which is similar to the area of the corresponding face. The closures 20 are shown in the open condition. Thus the closures provide access to the full heightlwidth of the housing when opened. The closures 20 and/or faces 16, 18 may provide a sealing engagement when closed, for example about the periphery of the closures. Each closure has a lock mechanism of conventional type, e.g. mounted on its interior surface.

The housing is generally rectangular in plan and/or in section so as to form a hollow box-like enclosure when closed.

The lid 22 is held in place using conventional fasteners that can be released as required, typically from the interior side of the housing only, to allow the lid to be removed from the remaining walls.

At least one side wall, i.e. wall 12, has a slot 26 extending from its upper edge to a location part way down the wall. The slot opens at the upper edge of the wall 12 and terminates at a rounded end. The end accommodates a shaft 24 as will be described below. In figure 2, the shaft 24 is shown with a schematic of a boom 28 mounted thereto on the exterior of the housing 10. The boom is typically mounted on a free end of the shaft by a keying/locking arrangement so that the boom rotates in unison with the shaft in use.

Any conventional type of boom 28 may be used, which may or may not be cantilevered. The boom typically comprises an elongate pole of between 3 and 10 metres in length. The boom may be below 9 metres in length. The boom may have a conventional curtain or other accessories, such as signage and/or lights.

Turning now to figures 3 and 4, there are shown respective front and rear views of the housing 10 with a boom actuation system mounted therein. An electric drive system 30 is shown in Figure 3, which is mounted to a support frame in the form of a chassis that can be attached within the housing 10. The chassis provides a rigid S support structure to which the various components and/or sub-assemblies of the actuation system can be mounted in isolation of the housing. The support structure thus holds the boom actuation system in the desired relative configuration for use and may thus alleviate some of the load-bearing requirements of the housing.

The support structure comprises a first set of attachment points to which the boom actuation system can be mounted and a further set of attachment points, via which the support structure is attachable to the housing. Any of those attachments points may comprise apertures and/or conventional fixings or fasteners, such as bolts, screws, studs or other male/female connector formations.

It can be seen that the chassis comprises a dividing wall 34 or bulkhead, which spans the width of the frame and interior of the housing 10. The chassis comprises one or more further cross member 36 (see Figure 4), such as a beam, bar or similar, providing structural strength to the chassis in a lateral direction. The chassis comprises a plurality of upright/vertical support members 38, to which the gearbox is mounted by fasteners 40. Although not show in figures 3 and 4, due to being hidden by the housing walls, the chassis comprises upright support members at its lateral edges or apexes, thereby forming a frame-like structure within the perimeter of which the boom actuation system is held.

The frame may be a three dimensional frame structure which may be substantially rectangular in plan and/or section (e.g. having a rectangular footprint).

In Figure 4, a manual actuation system 32 is shown. The manual actuation system 32 is mounted on the opposing side of the dividing wall 34 than the electric drive system 30. Accordingly each system is separated by the wall 34 and accessible from opposing directions by respective closures 20 on the front and rear faces of the housing.

The manual actuation system 32 comprises a handle 42, arranged to allow manual torque input about a pivot. The handle42 is operably connected to (i.e. in torque communication with) a toothed gear wheel or pinion 44 (e.g. by an intermediate gear), which communicates with an elongate toothed actuator member 46, such as a bar or rack. The member 46 has teeth arranged laterally along its length. At the upper end of the elongate member 46 is selectively connectable to a drive arm 48 on the shaft 24 as will be described in further detail below.

Thus manually turning the handle can raise or lower the member 46, depending on the direction of rotation of the handle, which, when engaged with drive arm or lever 48, can turn the shaft 24 in a clockwise or anti-clockwise direction to lower or raise the barrier. The member 46 may be selectively coupled to the drive arm 48, for example by a pin connector insertable through a corresponding aperture 50 in the drive arm. In this embodiment, the aperture 50 is an elongate slot to allow travel of the connector pin along the slot at the drive arm rotates. The drive arm in this example has a split/forked end to receive the member 46 therebetween. The member 46 may be lowered for storage.

Figures 3, 5 and 6, show the electric drive system 30 which is permanently connected to the shaft 24. The electric 30 and manual 32 drive systems are connectable to the shaft in a parallel force communication arrangement. However the selective coupling of the manual system 32 as described above means that only one of the drive systems will typically be used at any one time. Thus the manual system 32 provides a backup in the event that the electric system fails.

The electric drive system 30 comprises a three-phase electric motor 52 coupled to a direct drive gearbox 54. The shaft 24 passes through the gearbox 54. The output torque from the rotor of the electric motor 52 is communicated through the gearbox 54 to a gear wheel (not shown) on the shaft 24 located within the gearbox. The gearing causes the shaft to rotate significantly more slowly than the motor, such as to provide boom raise and lower times of between approximately 6 and 10 seconds (i.e. for the shaft 24 to rotate through approximately 90°). In examples of the invention a 0.37-1.5 kW electric motor having 2-8 poles has been found to be suitable. A larger number of poles has been found to offer beneficial control of boom movement.

The motor 52 and gearbox 54 are rigidly coupled together so as to provide a common subassembly. The subassembly is attached to the intermediate wall/bulkhead 34 in an upright orientation using fasteners, such as bolts.

The motor and gearbox assembly in this example preferably comprises an internal braking mechanism to selectively prevent rotation of the rotor/shaft as and when required. The braking mechanism may be applied to inhibit rotation of the shaft 24 under one or more failure modes of the actuation system, for example upon detection of: loss of electrical power to the actuation system; incorrect shaft rotation/movement; and/or loss of torque to the shaft. In this regard, the braking mechanism may allow the boom to be retained at the angular orientation at which a failure occurred. In one or more further embodiments, the actuation system may allow for release of the braking mechanism, e.g. manually or upon receipt of a control signal (e.g. remotely), to allow the boom to fall to the lowered condition under gravity.

In either a braked or unbraked example of the invention, the actuations system may comprise a boom lowering or damping arrangement, for example to allow controlled lowering of the boom under failure of the electric drive. Thus if power to the electric motor is shut off whilst the barrier is not in the lowered position, the boom may fall under gravity to the default lowered position in a controlled manner.

The boom lowering arrangement may comprise a hydraulic system, thereby allowing controlled rotation of the shaft whereby the torque applied by the weight of the boom is resisted by fluid pressure in the hydraulic system. Alternatively, the boom lowering system could comprise a controlled release of the electric drive braking mechanism. Depending on specific operational requirements, it may be beneficial to provide a system in which the boom retains a current orientation in the event of failure of the actuation system (e.g. by holding the boom/shaft 24 at fixed angular orientation). Alternatively it may be desirous to provide a damping/lowering mechanism to ensure that the boom will fall safely and in a controlled manner to a lowered condition upon failure of the actuation system.

The shaft 24 extends in a substantially horizontal direction through the gearbox 54 such that the shaft overhangs the gearbox on opposing sides thereof. The shaft is preferably formed of a high grade steel. A first portion 24A of the shaft protrudes through the housing wall to the exterior and provides the mounting point for the boom. The second portion 24B of the shaft extends from the opposing side of the gearbox 54 within the interior of the housing in use. A mounting bracket/bearing 56 is provided on each side wall 12, 14 of the housing, typically on the interior surface thereof such that the shaft is supported by the housing towards its ends.

Whilst Figure 5 shows a further shaft extension portion 24C protruding beyond the mounting 56, such a shaft feature is optional. Such a shaft feature may be applicable to a test environment and/or may be used in the field, for example to apply a counterbalancing mass for larger/heavier boom applications.

The second portion 24B is longer than the first portion 24A and provides a mounting region for a plurality of further components, 48, 58 and 60. Those further components may be collectively referred to as radial members' or arms since they all depend radially outwardly from the shaft. All of those radial members are rigidly connected to the shaft for rotation therewith in use (i.e. in unison). However the further members typically comprise a plurality of different types of radial member as will be described below.

The drive arm 48 has been described above and provides a lever for application of torque to the shaft 24 by the manual actuation mechanism 32. The drive arm typically depends radially outwardly from the shaft to a greater extent than the members 58. The drive arm may also serve as a stop member to limit the freedom of rotation of the shaft in use, e.g. by abutment with an opposing stop member (not shown) mounted in place on the interior of the housing.

A further stop arm 60 is provided spaced from arm 48, towards the end of the shaft 24. The stop arm is arranged to limit the freedom of rotation of the shaft 24. The stop arm may be arranged to abut corresponding/opposing formations in the housing or else on the chassis at the desired rotational limits of the shaft. The stop arm rotates with the shaft and may be arranged to limit rotation to approximately 900, such as between horizontal and vertical boom orientations. In any example of the invention, the rotation of the shaft may be slightly less than 90°, such as approximately 85°.

The radial member labelled 58 is a shaft angular orientation indicator. A plurality of such indicators may be provided side-by-side along the shaft as shown in Figures 5 and 6. As side view of one orientation indicator 58 is shown in Figure 8. It can be seen that the indicator 58 takes the form of a cam-like plate, having a curved/arcuate outer surface 62 that extends about a portion of a circular arc about the shaft rotation axis. Thus the indicator is shaped in plan like a circular sector. The plate is mounted on the shaft by a locking ring 64 and the precise angular position of the plate leading/trailing edge can be adjusted using a limit screw adjuster mechanism 66.

In use a plurality of indicators 58 are mounted in angularly offset positions about the shaft. An orientation sensor plate 68 is mounted relative to the shaft at a predetermined distance from the shaft axis. The sensor plate 68 is spaced so as to offer a minimal or small clearance from the outer edges 62 of the indicators 58 as they rotate past the plate in use. The plate 68 has a plurality of apertures for proximity sensors (not shown). The proximity sensors face towards the shaft so as to be able to detect the presence or absence of an indicator 58 adjacent to the plate 68 in use. Whilst a plate is preferred in this example, other sensor mounting means could be used as necessary.

The indicators are angularly staggered so as to accommodate the full angular sweep of the shaft in use. Thus at least one indicator will be detected by the proximity sensors at every point during rotation of the shaft in use. In this way the angular position can be determined to be within one or more zones or regions within the the limits of angular travel of the shaft.

Turning back to Figure 3, a control unit 70 is indicated schematically as being mounted within the housing. The control unit 70 may or may not be mounted to the chassis. In one example it may be possible to mount the controller to the chassis and connect the controller to the relevant components of the actuation system whilst on the chassis, but prior to installation within the housing. Thus the time on site is minimised, since only a minimum of electrical connection are required to be made, including hook up to an external power supply, etc, and the electronics can be connected up internally without access being inhibited by the housing.

The control unit comprises one or more processors having machine readable code for the operation of the actuation system to control raising and lowering of the boom in a prescribed manner. The control unit has wired or wireless communication means for receiving control signals from a remote location.

During manufacture/assembly, the lid 22 of the housing 10 is removed and the chassis, having the above-described actuation system mounted thereon, is inserted into the housing from above until the lowermost end of the chassis rests on the housing base. The chassis is then attached to the housing by fasteners.

The lid may then be replaced. Thus a pre-assembled barrier unit/module may be provided.

Once on site at the intended barrier location, the boom is attached to the shaft end 24A and external power and communications lines can be connected as required.

In use, the control unit receives control signals to raise/lower the barrier and instructs operation of the electric motor to angularly displace the shaft. The sensor readings for the shaft orientation indicators 58 are received by the control unit, which varies the rotational speed of the shaft 24 between lowered and raised conditions accordingly. In particular, the electric motor initially accelerates the shaft to a predetermined maximum rotational speed during a first stage of actuations. The rotational speed may be held approximately constant during a second stage of actuation. Once a further indicator 58 has passed a sensor, indicative of the proximity of the boom to a final raised or lowered condition, the control unit may instruct deceleration of the electric motor at a predetermined rate or else according to a predetermined deceleration curve so as to prevent stress on the system caused by sudden cessation of the boom shaft. Due to the elongate hollow boom profile, such a control scheme is particularly important to prevent undesirable flexing of the boom upon stopping.

In Figures 7A and 7B, an end view of the shaft is shown in the lowered and raised conditions respectively. The barrier (not shown) is substantially horizontal in the lowered condition and substantially vertical in the raised condition. Arm 48 is offset from the angular orientation of the barrier and is obliquely angled relative thereto.

In this example, the arm 48 is approximately 45° above and below horizontal in each of the respective lowered and raised conditions.

Turning now to Figure 9, an alternative arrangement of the drive system 30A is provided. This arrangement is substantially as described above, save that the stop member 60 has been removed. Instead the function of the stop member 60 has been integrated into the drive arm 48A. The angular orientation of the arm 48A can thus limit the angular range of movement of the shaft. Opposing abutment formations (not shown) may be provided on the chassis or interior of the housing to limit the available rotation of the arm 48A. The arm 48A may rotate through approximately 900 between upper and lower orientations that are offset from horizontal/vertical. The obliquely angled orientation of the arm 48A allows it also to be used as the drive arm for the manual over-ride mechanism.

In Figure 9, the shaft portion 24B can also accommodate a greater number of radial members 58, i.e. four members in this example. The increased number of orientation indicators allows further delineation between different portions of the rotational actuation of the shaft 24, thereby allowing the shaft to be actuated at different speeds with greater control for raising and/or lowering operations. In other examples, it may be beneficial to provide five or six orientation indicators (i.e. limit cams) for greater control.

In Figure 10, further optional features of the invention are shown. In particular, in Figure 10 a mounting 72 for a boom/barrier assembly is shown, which is rigidly attached to shaft end 24A for rotation therewith in use. The mounting 72 comprises a body 74, which provides a cantilever portion of the boom assembly.

S The body 74 is generally planar or plate like in form and comprises spaced openings 76 and 78. The openings 76, 78 are arranged at a substantially equal radial distance from the rotational axis of the shaft 24 but are angularly offset, for example by approximately 90°, or slightly less, for example 85°. A corresponding opening (not shown) is provided is provided in the housing wall 12 and/or chassis structure. That opening is generally aligned with the opening 78 in the lowered barrier condition as shown in Figure 10 but would be aligned with opening 76 in a raised condition. A pin may be inserted through the aligned openings to lock the barrier in place for example during maintenance work or else as a safety measure during disconnection/failure of the electric drive.

As can be seen in Figure 11, the openings 76, 78 may have a corresponding boss or strengthening member 80 on a reverse side of the mounting 72.

Turning now to Figure 11, there is shown a further example of a manual actuation system/mechanism 100 in place of that described above in relation to Figure 4.

The manual actuation system 100 may be mounted to the chassis in a manner described above. The actuation system 100 comprises a fluid pressure, i.e. hydraulic, actuation system. A piston-and-cylinder arrangement 102 is mounted to the chassis and permanently connected to the drive arm 48 or 48A described above. A free end of the piston is pivotably connected to the drive arm in this

example.

A fluid reservoir 104 is fluidly connected to the cylinder by a valve arrangement 106. A manual actuator 108 is provided, which in this example comprises a connector for a handle. The manual actuator is moveable back and forth to provide a pumping action for the fluid in the hydraulic system 100.

The valve arrangement controls flow of hydraulic fluid in the system 100 to/from the cylinder. Two valves may be provided in flow paths to/from the reservoir 104 or cylinder 102. In normal use the valves allow free/passive flow of fluid in the hydraulic system. The flow of hydraulic fluid thus does not drive actuation of the S barrier in normal use but may be used to provide a damping mechanism, for example whereby the flow of fluid in the hydraulic system restricts the speed with which the boom can rotate, for example in the event of failure of the electric drive.

However, when one or both of the valves 106 are switched, the flow to/from the cylinder is restricted so as to allow the fluid pressure in the cylinder to drive or control boom operation. The hydraulic arrangement allows bi-directional actuation so that the barrier can be manually driven to raise and/or lower the barrier. A further valve may be provided to select the direction of barrier actuation by the manual pump mechanism. Thus the values 106 can be used to control flow between the reservoir and cylinder regardless of whether the pump is in a manual actuation mode or not.

The valves 106 in this example are advantageously actuated by the closure 20 (i.e. the door of the housing). In this regard one or more projection 110 may be provided to engage the valve actuators when the closure is closed and disengage the valve actuators when the closure 20 is released/opened. A locking mechanism on the closure thus ensures when the closure is closed the hydraulic system 100 operates in a normal/passive mode. However, when the closure is opened/unlocked to allow manual intervention, the flow to/from the cylinder 102 is controlled to allow a hydraulic actuation force to be applied.

The valves 106 may be operated by depression of corresponding valve actuators, i.e. push buttons, in this example which are contacted by the closure 20 upon closing.

The locking pin arrangement described above is useful in combination with the manual actuation system in order to provide safe actuation and locking of the barrier for maintenance, inspection, assembly, disassembly or other in-situ work as may be required.

Any of the features described above in relation to the embodiments of any one of Figures 9 and 10 may introduced either in isolation, or in combination, with any of the embodiments described with reference to Figures 1-8.

The above described boom actuation systems are beneficial as the shaft is cantilevered on either side of the gearbox. Due to the actuation system and supporting chassis arrangement, the embodiments described above provide a heavy-duty barrier which is simple to install and can operate for long periods of time with low maintenance requirements.

The above examples concern a rail/road barrier, which may be used e.g. as a safety barrier to control access to a railway crossing or may be used as a security barrier to selectively permit access to a location or site via the barrier.

Claims

CLAIMS: 1. An access barrier comprising: a housing; S a boom depending from the housing, the boom being pivotably mounted to allow the selective raising and lowering of the boom in use; and a boom actuation system comprising an electric motor and gearbox arranged such that an output torque from the motor is transferred to the boom via the gearbox, wherein the boom actuation system is mounted to a common support frame, the common support frame being removably insertable into the housing.
2. A barrier according to claim 1, wherein the common support frame comprises a chassis.
3. A barrier according to claim 1 or 2, wherein the support frame comprises a plurality of upright support members and one or more cross members extending between said upright support members, at least one of said members being a dividing wall arranged to span the interior of the housing.
4. A barrier according to any preceding claim, wherein the support frame comprises a first set of mounting points for the boom actuation system and a further set of mounting points for attachment to the housing.
5. A barrier according to any preceding claim, wherein the support frame is insertable into the housing from above.
6. A barrier according to any preceding claim, wherein the boom actuation system comprises a shaft passing through the gearbox, the boom being mounted to said shaft.
7. A barrier according to claim 6, wherein the shaft comprises a first portion to which the boom is attached, the first portion extending from one side of the gearbox to an end of the shaft located externally of the housing, and a second portion depending from a second side of the gearbox through the interior of the housing.
8. A barrier according to claim 7, wherein one or more of a shaft angular S orientation indicator and/or a manual shaft actuation link member are mounted on the second portion.
9. A barrier according to claim 7 or 8, wherein one or more radial members depend outwardly from the second portion of the shaft.
10. A barrier according to any one of claims 6 to 9, wherein the boom actuation system further comprises a manual actuation mechanism and the shaft comprises a common shaft for both the manual actuation mechanism and the gearbox.
11. A barrier according to any one of claims 6 to 10, wherein the manual actuation mechanism comprises a handle and a gearing in the force path between the handle and the shaft, the manual actuation mechanism being selectively engageable with the shaft.
12. A barrier according to any one of claims 6 to 10, wherein the manual actuation mechanism comprises a fluid pressure actuator and a handle to allow application of pressure to the fluid pressure actuator.
13. A barrier according to any preceding claim, comprising a manual actuation mechanism for the boom mounted to the support frame.
14. A barrier according to any preceding claim, comprising a damping mechanism for controlling movement of the boom, for example in the event of failure of the electric motor.
15. A barrier according to claims 13 and 14, wherein the damping mechanism and the manual actuation mechanism are common.
16. A barrier according to any preceding claim, comprising a control unit mounted to the support frame.
17. A barrier according to any preceding claim, comprising one or more angular S orientation sensors, typically for determining the angular orientation of the boom, the speed of rotation of the boom being controlled in accordance the output of the angular orientation sensor.
18. A method of forming an access barrier comprising: providing a boom actuation system including an electric motor and a gearbox, the gearbox being operably mounted to a shaft for driving the boom in use; mounting the boom actuation system to a common support frame; and inserting the support frame with the boom actuation system mounted thereon into a housing.
19. A boom actuation system for an access barrier comprising: an electric motor and gearbox arranged such that an output torque from the motor is transferred via the gearbox to a shaft passing through the gearbox, wherein the shaft has a first portion extending from a first side of the gearbox for connection to a boom in use and a second portion extending from a second side of the gearbox, the second portion of the shaft comprising a mounting for one or more angular orientation member depending radially outwardly from a shaft axis.
20. A boom actuation system for an access barrier substantially as bereinbefore described with reference to the accompanying drawings.