Abstract: A telescoping security device comprises of a housing having a top and a bottom portion, wherein the housing is installed below ground, a first tube, having a first and second end, wherein an outer section of the first end of the first tube is mounted on the bottom portion of the housing, and wherein the first tube has an inner stopping means positioned near the first end of the first tube, and wherein the first tube is installed below ground, a second tube, having a first and a second end, placed within the first tube, wherein the second tube has an outer resting means at a position near the second end of the second tube, for resting on the stopping means of the first tube, and a stabilizing means for stabilizing the second tube within the first tube attached to the first tube within its first end. Ideally the device's second tube would have a handle attached within the first end of the second tube.

Abstract: A railroad crossing gate is repaired by lowering the crossing gate mechanism with a lever. The end of the lever can contain a conical opening mating with the conical pivot pin on the gate mechanism.

Abstract: A removable traffic control bollard has a post and a base for removably receiving the post. The post has a depending cylindrical part that fits into the tube of the base, held by rider elements that fit inside an upper post member of hollow tubing. The base has a faceplate opening into a downwardly depending tube that is embedded in the ground, or the like, preferably with the faceplate at surface level. The faceplate has two locking apertures over a box, and the post has an aperture in a cleat, through which apertures a padlock U-bolt can be inserted to lock the post to the base. The post can be repeatedly inserted into the base and locked into position and, if desired, subsequently removed by unlocking it and pulling it up out of the base.

Abstract: A system is disclosed for providing a backup power supply for a security gate system. In a preferred embodiment it includes a primary power supply, an AC motor and an auxiliary DC motor that share the same accessory devices including controller, movement mechanism, sensors, communication unit, etc. The auxiliary DC motor has its own independent DC power supply. If the primary power supply fails the auxiliary power supply takes over and moves the barrier between the open and closed positions as needed without interruption of service.

Abstract: A one piece modular automatic lift gate comprising a lift stump, a lifting arm, at least one stanchion, a slab, a control box set inside a stanchion to house mechanical, electric and electronic components.

Abstract: This invention relates to an electromechanical barrier, which comprises a movable bar (10) fixed and turning with a shaft (14) supported in a body, and at least one spring balancing means to balance the bar during its movements between an open and closed positions. A secondary shaft (20) is housed in the body parallel to the bar rotating shaft (14), a driving gear (21) couples the bar rotating shaft (14) to said secondary shaft (20) so that one turn of the former corresponds to one turn in proportion of the latter, and said at least one spring balancing means (22) is connected with said secondary shaft (20).

Abstract: A barrier gate includes a crossbar selectively pivoting between a saddle post and anchor post. The crossbar includes a first end and a second end. The first end of the cross bar is pivotally secured to the anchor post such that the second end of the crossbar may be selectively lifted from the saddle post opening the barrier gate and providing access therethrough. The barrier gate also includes a locking mechanism at the first end of the crossbar for permitting the selective locking of the crossbar in a substantially vertically orientation. The barrier gate further includes a counterweight interacting with the crossbar for assisting in the lifting of the crossbar between a closed orientation and an open orientation, and a cable linking the counterweight to the crossbar.

Abstract: A railroad crossing gate assembly is provided that includes a gate arm adapter, which is pivotally mounted to allow a lowered gate arm to rotate away from a generally perpendicular force in a generally horizontal plane either toward or away from a railroad crossing. The gate arm mechanism further includes multiple interchangeable spring assemblies that generate a return force to bring a displaced gate arm back to its normal operating position, and at least two latch hook assemblies for selectively latching the gate arm in its normal position and controlling the rate of return of the gate arm from a displaced position through application of a pivotally leveraged force to a braking surface.

Abstract: A frame assembly for making a gate or door comprising an upper horizontal member, a lower horizontal member, a first vertical member and a second vertical member, one or more support members provided along the length of each of the upper and lower horizontal members, first connection means to connect an upper end of the first vertical to one end of support member provided along the length of the upper horizontal member, second connection means to connect lower end of the first vertical to one end of support member provided along the length of the lower horizontal member, third connection means to connect an upper end of the second vertical to a second end of support member provided along the length of the upper horizontal member and fourth connection means to connect a lower end of the second vertical to a second end of support member provided along the length of the lower horizontal member.

Abstract: A railroad grade crossing assembly including a programmable controller. In a preferred embodiment, the crossing assembly includes at least one camera for the purpose of visually monitoring the crossing assembly and/or the area around the assembly. In another preferred embodiment, the crossing assembly includes a communication link for remotely monitoring and/or controlling the assembly.

Abstract: This invention relates to an overhead door closer with slide arm assembly (1) having a toothed pinion (6) that is eccentrically supported and presents a circular rolling curve, which pinion meshes with a toothed rack (5) arranged at a piston (4). The invention concentrates on a particular embodiment of the rolling curve and of the teeth (9) of the toothed rack (5) in adaptation to a toothing of the pinion (6). Furthermore, the invention concentrates on an improved embodiment of the delayed closing operation in order to achieve an optimized movement pattern of the piston (4) within the housing (2) of the overhead door closer with slide arm assembly (1).

Abstract: A car or other vehicle is prevented from crashing through a barrier along a driveway or other path. One or more bollards stands in the path, on a support in a recessed box that is flush with the surface and defines a pivot axis perpendicular to the path of the vehicle. The bollard can be temporarily detachable to permit passage. A vehicle striking the bollard pivots the bollard backward on the axis, preferably into a clearance space provided. Elongated pike structures are coupled to the bollard and are pivoted up from the surface at an acute angle, to pierce and arrest the vehicle. The pikes can be structural bars, for example of angle iron with flanges formed to barbed points. Preferably several pikes are provided, of which some are angularly fixed relative to the bollard and others are rotatable up to a maximum angle at which the pikes become angularly stopped, for example by engagement with the adjacent pikes. The pikes thus are deployed in a bristling array that engages with the vehicle.

Abstract: On a spring-biased safety gate, a guard plate is mounted to a gate member with the same hardware that mounts the stop to the gate. The guard plate is preferably formed of plate metal to define a plate mounting area and a pair of guard plates that extend perpendicularly from either side of the plate mounting area. In that way, each of the pair of guard plates extends in a direction parallel to the gate a distance sufficient to shield the mounting hardware behind the guard plate and the stop.

Abstract: A railroad gate release mechanism which attaches between the mount arms of a railroad gate actuator and a crossing arm to prevent breakage of the crossing arm due to impingement by a vehicle. The railroad gate release mechanism includes a pivotable arm assembly which allows released movement in two directions of the crossing arm in reaction to impingement and returns the crossing arm to the original and detented position subsequent to impingement to maintain grade crossing protection. An alternative embodiment includes a pair of swing plates and an elongated arm to which is attached a crossing arm, the elongated arm with the attached crossing arm is pivoted to the pair of swing plates in such manner that the elongated arm and attached crossing arm can be pivoted aside without moving the swing plates for crossing arm maintenance without impeding vehicular traffic flow across the grade crossing.

Abstract: A framed gate pivotally mounted at one of it's lower corners to an inner fence post securely positioned in the ground. The pivotal mounting of the gate allows one end of the gate to swing up and out of the way thereby effectively opening a gap and allowing passage from one side of the fence line to the other. A primary post is positioned outside of the inner fence post in relation to the gate. A manual winch device or powered winch device is attached to the primary post for the lifting of the framed gate. Further, this device is equipped with a spring for assisting the swinging of the gate up and out of the way and may be equipped with a remote control mechanism for remote operation of the gate. On the opposite side of the gate from the inner post is located the outer post which contains a catch mechanism to engage a locking mechanism on the gate to securely lock and hold the gate in a closed position.

Abstract: An underground gate system for use with driveways and many other applications. The system includes plural posts which are hydraulically raised and lowered to blocking or open positions. In the up position, the posts stand 18-36 inches tall and include decorative lighting for safety and visibility. In the down position, the gate elements are virtually invisible. A particular hydraulic control system is also disclosed. The system is designed to be controlled from an in-car or in-house location.

Abstract: A pylon or barrier arrangement which is recessed into the ground or other surface and includes a post-like pylon which is movable between an extended position for control of vehicular or pedestrian traffic, and a retracted position beneath the ground. Movement of the pylon is achieved by a linear-type drive mechanism which acts as a clutch by decoupling from an upright and rotatable smooth drive shaft during abrupt downward driving of the pylon to avoid damage to the internal components of the arrangement. A sealing arrangement is provided for preventing the entry of debris into the interior of the pylon arrangement, and a heating unit is provided for preventing seizure of the arrangement during harsh weather conditions.

Abstract: A guide device for guiding drivers and their vehicles into and out of vehicle parking spaces. The guide device comprises an operating arm, which is attached to a surface by two brackets, namely an outer bracket and an inner bracket. A cam plinth is situated between the two brackets. The guide device is arranged such that the arm can pivot relative to the brackets.

Abstract: A railroad grade crossing assembly for blocking vehicle access across a railroad crossing including a gate assembly connectable to a stanchion and light assembly. This gate assembly is movable between a generally upright position to permit vehicle access across a railroad crossing and a generally horizontal position for blocking vehicle access across the railroad crossing. The gate assembly further includes a telescopic arm assembly for completely closing vehicle access to the railroad crossing. In another embodiment of the invention, the railroad grade crossing assembly includes a gate movable between a generally horizontal retracted position to permit vehicle access across a railroad crossing and a generally extended horizontal position for blocking vehicle access across a railroad crossing, the gate includes a telescopic arm for completely closing the railroad crossing, a first and second stanchions.

Abstract: On a spring-biased safety gate, a guard plate is mounted to a gate member with the same hardware that mounts the stop to the gate. The guard plate is preferably formed of plate metal to define a plate mounting area and a pair of guard plates that extend perpendicularly from either side of the plate mounting area. In that way, each of the pair of guard plates extends in a direction parallel to the gate a distance sufficient to shield the mounting hardware behind the guard plate and the stop.

Abstract: A hinge coupling and a lock for connecting a stationary handrail to a gate arm for a gate. The gate in closed position retains the structural integrity and peripheral profile of the handrail. The hinge coupling consist of a fixed connector and a mobile connector, both pivotally connected to a middle link by pins. The components of the hinge coupling pivot about the pins, enabling the gate arm to pivot through a 180° angle. One hinge connector is inserted and secured into an open end of the stationary handrail. The other connector is inserted and secured into an open end of the gate arm. The lock consists of two mating active and passive components that are fastened to respective terminal ends of the handrail and gate arm. The lock components are provided with a manually releasable latch. All components in the closed position of the gate compactly fit together and are shaped to provide peripheral continuity.

Abstract: A security gate drive mechanism is disclosed having a rotating shaft which rotates no more than a single rotation in order to provide through a linking mechanism, a driving force to move a security gate from a first position in which the security gate is essentially fully closed, to a second position in which the security gate is essentially fully open. A driving motor having a drive shaft rotating at much greater than one revolutions per minute, and a reduction gear contained in a reduction gear housing having an input shaft operatively connected to the drive shaft and an output shaft comprising or operatively connected to the rotating shaft, thus reducing the revolutions per minute of the drive shaft to a number of revolutions per minute suitable for operation of the security gate.

Abstract: A security gate is coupled via a positive-drive mechanical linkage to a DC gear motor, operative in response to a defined output voltage profile, to provide precise rotation and counter-rotation of the security gate through a defined range of motion.

Abstract: An apparatus for shifting a gate from a closed position to an open position on emergency from loss of power to a motive means. The apparatus generally comprises a housing along with a motive means, such as an electric motor, operatively associated with the housing. A drive member is operatively connected to the motive means and is capable of being connected to a gate for causing rotating movement of the gate. Typically the drive member is connected to the motive means by means of a drive shaft, which extends from the housing. The apparatus comprises a manually operable release member, which is operatively connected to a drive plate. The release member functions as part of an override means and is capable of being sheared on application of force, thereby releasing the drive plate from a base plate of the motive means operatively disconnecting the drive member from the motive means, and more particularly disconnecting the drive member from the drive shaft.

Abstract: An automated parking gate structure is disclosed having enhanced safety features for deterring accidents and providing greater protectibility against damage in the event the gate arm strikes a vehicle. The parking gate comprises a base cabinet, a control mechanism disposed within the cabinet, and a gate arm connected to the cabinet, adapted for motion relative thereto in response to operation of the control mechanism. A first light element is disposed along a first surface of the gate arm. The light element being in communication with the control mechanism to regulate operation of the light element in response to operational modes of the gate control mechanism.

Abstract: Throughway barrier apparatus comprises a pair of housings (51, 52; 151, 152) to be sited one to each side of a throughway (58). Each housing is provided with an upstanding surface (53, 54) of magnetic material, the two surfaces (53, 54) facing one another. A movable device (65) is magnetically coupled to each upstanding surface, and drive means (60) are arranged to move the magnetically coupled device upwardly and downwardly of the surface (53, 54). A barrier element such as a chain, cable, boom or the like extends across the throughway (58), the barrier element (55; 155a, 155b) being in use connected to the two said movable devices (65) for movement therewith.

Abstract: A device for prevention of theft of a vehicle and for keeping a parking space for a vehicle when the vehicle is not parked in the space. The device is a collapsible barrier controlled by a remote control. It has a novel mechanism of protecting accidental damage to cars and to the barrier itself. Protection is afforded by means of a biasing element built into the device which gives way when accidentally hit by an approaching car and then automatically returns to a vertical position. When the vehicle with the remote control approaches and is about to hit the barrier a warning alarm is sounded, or in another embodiment of this invention, the remote sensor in the device is automatically lowered when it senses the approaching vehicle. In another embodiment of this invention the collapsible barrier is secured onto a ceiling above a parking surface enabling a convenient electric source for the devices and easier maintenance and central control over numerous barriers placed in a large parking facility.

Abstract: A railroad gate release mechanism which attaches between the mount arms of a railroad gate actuator and a crossing arm to prevent breakage of the crossing arm due to impingement by a vehicle. The railroad gate release mechanism includes a pivotable arm assembly which allows movement of the crossing arm in two directions in response to the impingement and returns the crossing arm to the original and detented position subsequent to the impingement to maintain grade crossing protection. Spring assemblies, a shock absorber and a spring centering assembly act to return the pivotable arm assembly and attached crossing arm to the normal detented position.

Abstract: A railroad crossing gate is repaired by lowering the crossing gate mechanism with a lever. The end of the lever can contain a conical opening mating with the conical pivot pin on the gate mechanism.

Abstract: A method and apparatus for operating a security gate is disclosed which may comprise a drive mechanism arm having a first end and a second end, and including a security gate attachment member connected to the first end of the drive mechanism arm; a drive mechanism actuator operatively connected directly or indirectly to the drive mechanism arm and adapted to move the drive mechanism arm along a predefined path in relation to the actuator in response to operation of the actuator; and a release mechanism adapted to release the connection of the security gate attachment member to the first end of the drive mechanism arm in response to the application of a force to the security gate attachment member in a direction other than the force applied to the security gate attachment member by the drive mechanism arm in response to the operation of the actuator to move the security gate drive mechanism arm along the predefined path.

Abstract: The present device is directed to a new and improved barrier gate assembly which comprises an automatic vehicle gate operating mechanism and a barrier arm assembly. The barrier arm assembly, attached to the automatic vehicle gate operating mechanism, comprises of a bracket assembly with a hinge assembly attached thereto. The hinge assembly, having a pivot axis transverse to the bracket assembly, pivotally joins the bracket assembly to a plate assembly permitting pivotal movement of the plate assembly away from the bracket assembly. The plate assembly is fixedly attached to the hinge assembly for securing and holding a barrier arm. The barrier arm longitudinally extends from the plate assembly. A magnet-type device is provided on the bracket assembly in alignment with the plate assembly to hold both the plate assembly and the barrier arm in place next to the bracket assembly while preventing pivotal movement of the hinge assembly and thereby the extended barrier arm.

Abstract: A railroad grade crossing assembly for blocking vehicle access across a railroad crossing including a gate assembly connectable to a stanchion and light assembly. This gate assembly is movable between a generally upright position to permit vehicle access across a railroad crossing and a generally horizontal position for blocking vehicle access across the railroad crossing. The gate assembly further includes a telescopic arm assembly for completely closing vehicle access to the railroad crossing. In another embodiment of the invention, the railroad grade crossing assembly includes a gate means movable between a generally horizontal retracted position to permit vehicle access across a railroad crossing and a generally extended horizontal position for blocking vehicle access across a railroad crossing, the gate means includes a telescopic arm for completely closing the railroad crossing, a first and second stanchions.

Abstract: A blow-molded plastic, traffic control barricade. The assembly provides a hollow, blow-molded, louvered upright panel outfitted with warning indicia, lights and/or air passages that pivots from a molded hollow base. Braces mount between the base and upright panel. The panel and braces fold into a recessed cavity in the base and present a collapsed shape that occupies relatively little space and lends itself to stacking and erection and dismantling.

Abstract: A security device (2) is described for protection access to and from a parking space by being suitable for secure mounting to the entrance/exit of the parking space at ground level comprising a barrier or sign (9) capable of movement between a raised position for preventing movement of a vehicle past the barrier (9) and a lowered position permitting the vehicle to be driven over the device (2), and arming pedal (4) which is depressed when the vehicle is driven over the device (2) to energize a driving means in the form of a torsion spring (78) which is connected via a control means including a cam (40) having two cam lobes (42,44) for effecting movement of a bar (60), to the barrier (9) by a suitable connection means, such as for example a slotted wheel (84) and pulley arrangement, so that operation of the control means causes lower or raising of the barrier.

Abstract: A flexible gate is disclosed which comprises a plurality of segments. The segments may be connected by at least one coupling. When the flexible gate is acted on by a force, the flexible gate may flex. When the force is no longer present, the flexible gate may return to a substantially straight position. The segments may be removed or added as needed to repair broken segments or to adjust the length of the flexible gate.

Abstract: A flexible barrier system is described that can be lowered or raised from a remote location using an accompanying remote control device which is either lockable or not lockable. The motor and mechanics used to raise and lower the chain are modular for easy repair and replacement, and enclosed in a protective covering in order to protect them from damage or tampering.

Abstract: A railroad crossing gate mechanism is provided that includes a gate arm adapter which is pivotally mounted to allow a lowered gate arm to rotate away from a generally perpendicular force in a generally horizontal plane. The gate arm mechanism further includes multiple interchangeable spring assemblies that generate a return force to bring a displaced gate arm back to its normal operating position, and a latch hook assembly for selectively latching the gate arm in its normal position and controlling the rate of return of the gate arm from a displaced position through application of a pivotally leveraged force to a braking surface.

Abstract: The Articulated Parking Barrier, when deployed, prevents un-authorized automobile entry to adjacent parking spaces. This unique device is attached at the centerline dividing two adjacent parking spaces to prohibit unauthorized parking at one or both adjacent spaces. By this placement the opposing, right and left, articulated arms can be deployed independently as barriers to adjacent unoccupied parking spaces. When not deployed, the Articulated Parking Barrier appears to be nothing more than a metal divider post between two automobile parking spaces. Deployment and retraction of the articulated arms can be by hand or a remote-controlled, motor-driven mechanism.

Abstract: A apparatus for improving loading dock safety includes an actuator 22 coupled to light 16. Actuator 22 controls the position of a visible barrier 24, or flag. When semi-truck 12 is being unloaded, it is unsafe to move semi-truck 12 ahead, therefore, red light 18 is activated and actuator 22 lowers barrier 24 in front of the truck where the driver can see it. When the unloading process is complete, it is safe to move semi-truck 12 ahead, therefore, green light 20 is activated and actuator 22 raises barrier 24 to signal the driver that semi-truck 12 may be safely moved ahead.

Abstract: A safety barrier positionable across a path for deterring rolling objects from passing beyond the barrier includes an elongate hollow member having open lateral ends. The elongate hollow member includes a base for positioning on a surface and an upwardly extending wall having an arcuate concave surface for hindering rolling objects from passing beyond the barrier.

Abstract: A parking place obstruction for obstructing egress or regress to or from a parking space. The parking place obstruction includes a cylindrical sleeve with an open top end and a bottom end. The sleeve is adapted for mounting in a ground surface. A cylindrical shaft is telescopically inserted in the sleeve. The shaft is telescopically positionable between an extended position and a retracted position with respect to the sleeve. A plurality of locking fins are extendible from the shaft. The locking fins rest on the open top end of the sleeve for holding the shaft in an extended position when the locking fins are in the deployed position. A locking elements locks the locking fins in the deployed position.

Abstract: A crossing guard is disclosed which comprises an operator positioned on one side of a thoroughfare for raising and lowering an arm, a gate connected to the arm, a first lock positioned on the opposite side of the thoroughfare, a plurality of cables supported within the gate, joined together at fixed points intermediate the ends of the cables, and a first end assembly connectable with the cables and the gate at the end of the gate opposite the operator with the first end assembly engagable with the first lock. The device further comprises a second lock positioned on the side of the thoroughfare nearer said operator engagable with a second end assembly positioned on the end of the gate nearer said operator.

Abstract: An apparatus for blocking a parking vehicle from leaving, enabling a driver to confirm the locking board which is in the elevated state, and preventing the vehicle from leaving in an unauthorized manner. The apparatus does not employ any constitution for directly driving an auxiliary locking board using drive device, and the auxiliary locking board can be installed at a position remote from a main locking board.

Abstract: The safety crossing gate for a railway crossing of the present invention includes a secondary gate rotatably mounted or mountable to a primary crossing gate. The secondary gate is a rigid elongated member having first and second opposite ends. The second end of the secondary gate is rotatably mounted or mountable to a free end of the primary crossing gate by a rotatable coupling mounted or mountable to the second end of secondary gate and the free end of the primary crossing gate so as to allow selectively actuable rotation of the first end of the secondary gate relative to the primary crossing gate in a generally vertical plane containing the primary crossing gate when the secondary gate is rotatably mounted to the primary crossing gate by the rotatable coupling.

Abstract: A gate arm for retrofitting onto an existing cantilever crossing structure at a railroad crossing. The gate arm is pivotally attached to a mast of the existing cantilever crossing structure so that the gate arm can be lowered to an in use position and alternately raised to an out of use position. A cable extending from the gate arm to a winch secured to the cantilever crossing structure or mast lowers the gate arm in response to the approach of a train. Lights provided on the gate arm also activated in response to the approach of a train. The gate arm raises and the lights on the gate arm deactivated upon the train passing the crossing.

Abstract: Apparatus for controlling the flow of traffic through one or more traffic lanes includes a member that attaches to a traffic barrier such as a bar, a gate, or door. Under the control of an actuating element such as a control card, code entry, or manual switch, the member is rotated by an electric motor that drives a reduction gear connected through an adjustable slip clutch to a drive shaft connected to the member. The motor provides variable speed of rotation to the member so that the member will move more slowly at the beginning and end of its movement between open and closed positions of the barrier for safety of operation. The motor function is controlled by a microprocessor or microcontroller. The motor speed control may be by use of a DC motor powered by a current of DC pulses with variable pulse width. Alternatively, motor speed control may be by use of an AC motor with variable AC frequency power.

Abstract: An apparatus that prevents motorists from crossing railroad tracks, when the warning gates are down during approaching of a train consists, of a plurality of tire-piercing cogs which are retracted from the ground when the railroad crossing gate is closed. The cogs are arranged across the entire width of the automobile road in order to prevent a motorist from going around the closed gate through the oncoming traffic lane. The piercing cogs are interlocked with a warning visual and/or sound signal which is activated if the vehicle went onto the railroad tracks and stuck on the rails after smashing the closed road gate arm. The cog drive mechanism is located below the ground level, and when the gate is open for normal traffic through the railroad crossing, the cogs are turned into position in which their back surfaces are arranged in flush with the ground level for smooth passage of the vehicles.

Abstract: A parking lot management system including a plurality of parking space barriers each having a vertical member and an arm having an inboard end rotatably mounted to the vertical member. In use, the arm is adapted for pivoting about a vertical axis at least about 90 degrees. The parking space barriers each include a locking assembly for selectively fixing the arm with respect to the vertical member.

Abstract: A screw-threaded counterweight adjustment apparatus is journaled in end journals provided with brackets for attachment to the interior of a railroad crossing gate arm casing preferably by jam-type threaded fittings. A traveler is threaded over an elongated helically threaded rod rotatably mounted in the journals. A guide on one side of the traveler fits in an adjustment slot in the casing and a counterweight supporting rod or pin extends from the guide for attachment and support of the counterweights. The helically threaded rod is manually rotated by a wrench or by a motor to move the traveler and guide longitudinally on the counterweight section of the gate when it is desired to adjust the position of the counterweights.

Abstract: A safety pole is comprised of a strip of plastic material having a normal elongated hollow cylindrical condition with overlapping longitudinal edges. A motor driven drum is mounted within a canister adapted to be recessed in the ground in spaced relation to a loading dock with the strip of plastic material connected at one end to the drum whereby the strip of plastic material may be wound on the drum in a flattened condition or extended vertically upwardly to form a pole. A loading dock is provided with a door and the operation of the motor driven drum is coordinated with the operation of the door so that when the door is open, the pole will be in the extended visible condition to warn a truck driver not to approach or leave a loading dock.