Impact Absorbing Gate

Abstract

An impact absorbing gate includes a first upright having a first proximal end attached to a surface and a first distal end, a second upright having a second proximal end attached to a surface and a second distal end, an arm having a first end and a second end, the first end being pivotably coupled to the first distal end of the first upright at a pivot point, and a bistable mechanism disposed in the first upright and configured cause the arm to rotate to a fully opened position when the arm is rotated to an angle in a first range of angles and to cause the arm to rotate to a fully closed position when the arm is rotated to an angle in a second range of angles.

Description

BACKGROUND OF THE INVENTION

This invention relates to an impact absorbing gate.

Warehouses, distributions centers, factories, and similar facilities often have large stock handling equipment such as fork trucks which frequently move stock into, out of, and around the facility. In some examples, stock handling equipment moves stock between loading docks and shelving (e.g., pallet racks), often navigating through doorways and between shelving.

As an operator navigates stock handling equipment through a facility, there are often areas that are off-limits to the stock handling equipment (e.g., walkways) and areas where the stock handling equipment needs to be cautious (e.g., doorways and loading docks). When stock handling equipment enters those areas, damage or injury can be caused by collisions between the stock handling equipment and obstacles, pedestrians, and doorframes. Furthermore, stock handling equipment may inadvertently drive off an unprotected loading dock, damaging the equipment and seriously injuring the driver.

Because of the dangers associated with stock handling equipment traveling through facilities, barriers such as gates are often installed to control movement of the stock handling equipment through the facilities.

SUMMARY OF THE INVENTION

One type of barrier used to control movement of stock handling equipment through facilities is gates. Gates are often installed at doorways, loading docks, and along any path stock handling equipment may traverse. Gates are intended to prevent unintentional movement of stock handling equipment into designated areas. That is, an equipment operator has to deliberately open the gate, ensuring that the equipment operator is intentionally and safely entering the designated areas.

Conventional gates are prone to failure when struck by stock handling equipment such as forklifts, which can weigh more than 16,000 lbs. Some gate failures result in the stock handling equipment irreversibly damaging the gate while successfully stopping the equipment without undue danger to others in the facility. Other gate failures are more catastrophic, with pieces of the gate being ejected into the facility at high energy, potentially causing serious injury to people, product, and equipment in the facility.

Aspects described herein relate to an impact absorbing gate system that is designed to be struck by heavy stock handling equipment without incurring structural damage or catastrophically failing.

In a general aspect, an impact absorbing gate includes a first upright having a first proximal end attached to a surface and a first distal end, a second upright having a second proximal end attached to a surface and a second distal end, an arm having a first end and a second end, the first end being pivotably coupled to the first distal end of the first upright at a pivot point, and a bistable mechanism disposed in the first upright and configured cause the arm to rotate to a fully opened position when the arm is rotated to an angle in a first range of angles and to cause the arm to rotate to a fully closed position when the arm is rotated to an angle in a second range of angles.

Aspects may include one or more of the following features.

The impact absorbing gate may include an impact absorbing pivotable coupling attaching the first end of the arm to the first distal end of the first upright, the impact absorbing pivotable coupling including a hollow body extending through the first end of the arm, a bearing disposed within the hollow body, the bearing being rotatable relative to the hollow body, a resilient material disposed within the hollow body, and a fastener extending through the hollow body, the bearing, the resilient material, the first end of the arm, and the first distal end of the first upright. The pivotable coupling may be configured to permit movement of the arm with three degrees of freedom relative to the first upright.

The second upright may include an opening and a catch disposed in the opening, the catch including a notch, the second end of the arm may be configured to be received in the opening of the second upright and includes a pin configured to be received in the notch of the catch and, in the absence of a predetermined amount of force being applied to the arm, the pin is not received in the notch of the catch such that the second end of the arm can freely move out of the opening of the second upright and, in the presence of the predetermined amount of force being applied to the arm, the pin is received in the notch such that the second end of the arm is prevented from moving out of the opening of the second upright.

One or both of the first upright and the second upright may include a rotatable bumper. The rotatable bumper may include a cylindrical body configured to rest on and rotate about a cylindrical rail attached to the upright.

The impact absorbing gate may include a nylon strap extending through arm. The impact absorbing gate may include a pivotable coupling attaching the first end of the arm to the first distal end of the first upright. The nylon strap may have a loop disposed at its first end and a part of the pivotable coupling extends through the loop. A second end of the nylon strap may include a second loop and the second end of the arm includes a pin, wherein the pin extends through the loop.

The bistable mechanism may include a spring, a strut, and a linkage. The spring and the strut may be arranged coaxially, with the strut inside the spring. The first range of angles and the second range of angles may be separated by a threshold angle. The threshold angle may be adjustable. The threshold angle may be adjustable by adjusting a tension in the spring. The threshold angle may be adjustable by adjusting a configuration of elements of the linkage. The threshold angle may be adjustable by adjusting the strut. The first proximal end of the first upright may be attached to the surface using a first impact absorbing anchoring assembly and the second proximal end of the second upright may be attached to the surface using a second impact absorbing anchoring assembly.

The arm may be coupled to the surface through the bistable mechanism. The impact absorbing gate may include a second arm extending between the first and second uprights and rotatably coupled to the arm. The opening in the second upright may be tapered.

In another general aspect, a gate includes a first post assembly, a second post assembly having an opening and a catch disposed in the opening, the catch including a notch, a rail assembly with a first end rotatably coupled to the first post assembly and a second end configured to be received in the opening of the second post assembly, the second end including a pin configured to be received in the notch of the catch. In the absence of a predetermined amount of force being applied to the rail assembly, the pin is not received in the notch of the catch such that the second end of the rail assembly can freely move out of the opening of the second post and, in the presence of the predetermined amount of force being applied to the rail assembly, the pin is received in the notch such that the second end of the rail assembly is prevented from moving out of the opening of the second post.

Other features and advantages of the invention are apparent from the following description, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an impact absorbing gate in a closed configuration.

FIG. 2 is an impact absorbing gate in an open configuration.

FIG. 3 is a cross-sectional view of the first side of the impact absorbing gate.

FIG. 4 is a close-up perspective view of the first side of the impact absorbing gate.

FIG. 5 is a cross-sectional view of the pivot bearing of the impact absorbing gate.

FIG. 6 is a close-up perspective view of the second side of the impact absorbing gate.

FIG. 7 is a cross-sectional view of the rail of the impact absorbing gate.

FIG. 8 is a second embodiment of an impact absorbing gate shown in a closed position.

FIG. 9 is a transparent view of the impact absorbing gate of FIG. 8, showing internal mechanisms of the gate.

FIGS. 10 and 11 show a bistable opening/closing mechanism in a first post assembly of the impact absorbing gate of FIG. 8.

FIG. 12 is the impact absorbing gate of FIG. 8 in shown in a partially opened position.

FIG. 13 is the impact absorbing gate of FIG. 8 shown in a fully opened position.

FIGS. 14 and 15 show a catch mechanism in a second post assembly of the impact absorbing gate of FIG. 8.

FIG. 16 shows a strap retention mechanism.

FIG. 17 illustrates how the impact absorbing gate of FIG. 8 is coupled to a surface.

DETAILED DESCRIPTION

1 Overview

Referring to FIGS. 1 and 2, an impact absorbing gate 100 is configured for installation at a doorway or loading dock to prevent people or equipment from unintentionally passing into an area behind the gate 100. The gate 100 includes a first upright 102, a second upright 104, and an arm 105. Both uprights are anchored to an installation surface 101. The arm 105 has a first end 103 and a second end 107. A rail 106 extends from the first end 103 of the arm 105 to the second end 107 and the second end 107 of the arm 105 has an end piece 113 attached thereto.

The first end 103 of the arm 105 is pivotably coupled to a first distal end 115 of the first upright 102 using an impact absorbing hinge (not shown), described in greater detail below. When the impact absorbing gate 100 is in the closed configuration of FIG. 1, the latching member 113 at the second end 107 of the arm 105 secured in a second distal end 109 of the second upright 104 using a latching mechanism 111, described in greater detail below. A ribbon 108 hangs below rail 106 to block traffic (e.g., pedestrians) from going under the arm 105.

Referring to FIG. 2, the impact absorbing gate 100 is shown in an open configuration with the second end 107 of the arm 105 detached from and raised. As the impact absorbing gate 100 opens, the arm rotates about a vertical rotation axis 110 to allow traffic through a pathway between uprights 102, 104.

Referring to FIG. 3, the first end 103 of arm 105 is attached to the of first upright 102 using both an impact absorbing pivotable coupler (or hinge) 202 and a suspension mechanism 204.

2 Suspension Mechanism

The suspension mechanism 204 includes a first end that is attached to a first attachment point 217 at a proximal end 215 of the first upright 102 and a second end of the suspension mechanism 204 that is attached to a second attachment point 219 disposed on the arm 105 at a location separated from the vertical rotation axis 110. In some examples, the suspension mechanism 204 includes a compressed non-linear spring coil 206 configured to provide a specific torque profile corresponding to a range of vertical orientations of the arm 105. Due to the torque profile of the spring, the torque resulting from the weight of the arm 105 at any vertical orientation of the arm 105 is counterbalanced by the torque caused by the force of the spring coil 206 applied to the attachment point 219. As a result, the arm 105 is held in place at any vertical orientation of the arm 105 within the range. Furthermore, the suspension mechanism 204 reduces an amount of force required from a person to open and close the gate (i.e., to move the arm 105 through the range of vertical orientations).

In some examples, suspension mechanism 204 may include a cartridge 208 containing pressurized gas or fluid to provide further force in the suspension mechanism 204 pneumatically or hydraulically. In some examples, the suspension mechanism 204 replaced by an electrical actuator to control the movement of rail 106. Compression spring assembly 204 may also have a damping mechanism, such as having a damper inside spring coil 206.

3 Pivotable Coupler

Referring to FIG. 4, very generally, the impact absorbing pivotable coupler 202 couples the arm 105 to the first upright 102 in a way that allows the arm of the gate to move with three degrees of freedom (lateral movement about a lateral rotation axis 216, vertical movement about the vertical rotation axis 110, and rotation about an arm rotation axis 214 extending along the arm) without incurring damage. As is described in greater detail below, movement lateral movement about the lateral rotation axis 216 and rotation about the arm rotation axis 214 is limited by a resilient member that causes the arm to move and rotate back to its original lateral and rotational positions after a force of impact is removed.

In some examples, the pivotable coupler 202 includes a bearing assembly 422 having a hollow cylindrical body 424 with an internal rib 426. A pivotable bearing 429 is set in the internal rib 426. The bearing assembly 422 is partially encased in a resilient material 428 (e.g., an elastomer). A fastener 420 (e.g., a bolt) extends through the pivotable coupler 202, the first end 103 of the arm 105, and a part of the first distal end 115 of the first upright 102 to complete the coupling of the arm 105 to the first upright 102. In extending through the pivotable coupler 202, the fastener 420 extends through the resilient material 428 and through the pivotable bearing 429.

When the arm 105 is struck, the connection between the fastener 420 and the pivotable bearing 429 permits movement of the first end 103 of the arm 105 in all three degrees of freedom described above. Lateral movement of the arm about the lateral rotation axis 216 and rotation about the arm rotation axis 214 causes compression of the resilient material 428 by the fastener 420. When the force of impact is removed from the arm 105, the resilient material 428 forces the arm to return to its pre-impact orientation about the lateral rotation axis 216 and to its pre-impact rotational position about the arm rotation axis 214. In this way, movement of the arm about the lateral rotation axis 216 and rotation about the arm rotation axis 214 is permitted while preventing damage to the connection between the arm 105 and the first upright 102.

In some examples, the hollow cylindrical body 424 of the bearing assembly 422 increases a surface area of the bearing assembly to reduce the possibility that the bearing assembly tears out of the resilient material 429 when the arm 105 is struck.

4 Alignment Elements

Referring to FIG. 5, in some examples, the first distal end 115 of the first upright 102 includes a number of alignment elements 302 positioned between the arm 105 and the surrounding inner surfaces of first upright 102 such that, during movement of arm 105, direct contact between the arm 105 and the surrounding metal surfaces of the first upright 102 is prevented. The alignment elements 302 also ensure that that arm 105 is guided back a correct orientation when the gate is closed. The alignment element 302 are shaped to fit tightly into the respective spaces and can be made of soft or elastic materials with a desired compressibility, such as PTFE or other polymeric materials.

5 Latching Mechanism

Referring to FIG. 6, the distal end 109 of the second upright 104 includes a latching mechanism 111. The latching mechanism 111 is configured to receive and secure the end piece 113 of the arm 105 in a cavity 512 to hold the gate in the closed position of FIG. 2. When the end piece 113 is positioned inside the cavity 512, latching protrusions 504 extending through the inner side walls 514 of the second upright 104 and rest on top of the end piece 113 to prevent the end piece 113 from leaving the cavity 512.

The latching protrusions 504 can be retracted into the second upright 104 by moving the knobs 506, 508 in a direction toward the first upright 102. With the latching protrusions 504 retracted, the end piece 113 can be removed from the cavity 512. In some examples, the knobs 506, 508 are spring loaded such that they return to their original position (with the latching protrusions extended) once a user releases the knob.

The end piece 113 can be replaced in the cavity 512 to re-latch the gate by simply pushing the end-piece 113 into the cavity—the latching protrusions 504 are sloped such that they are pushed into their retracted position by the end piece 113 as it moves into the cavity 512. Once the end piece 113 is fully in the cavity 512, the latching protrusions re-emerge (by action of the spring 516) from the second upright 104 to rest on top of the end piece 113, once again securing the end piece 113 of the arm 105 in the cavity 512.

Knobs 506, 508 positioned on opposite sides of second upright 104 are attached to each other. This avoids the need for a user to reach across the arm 105 for the knob on the far side of the second upright 104 and therefore prevents injuries to the user in the event that the second end 107 of the arm 105 accidentally springs up and physically impacts the user. Knobs 506 and 508 are connected by a bar extending between them, each end attached to each knob. Knobs 506, 508 are designed to be exposed such that their open/closed positions are easily distinguishable by a user even from afar.

Optionally, there may be red/green indicators on each side of the upright 104 which switch between each other when knobs 506, 508 are switched from one position to the other. For example, the green indicators can switch to the re indicators when knobs 506, 508 are switched from open position to close position.

The arm 105 opens upwardly and the latching protrusions 504 are on top of the end piece 113 so that the latching mechanism is not damaged by a side impact by an object. The second end 107 of the arm 105 has an end piece 113 that is wider than the main body of rail 106 and is partially hollow to reduce weight. The end piece 113 prevents horizontal movement of the arm 105 when the gate 100 is in the close position. The arm 105 is made of plastic materials for safety reasons.

6 Arm Structure

Referring to FIG. 7 showing a cross-section along a plane perpendicular to arm 106, the internal structure of rail 106 includes a narrow hollow beam 602 positioned inside a wide hollow beam 604. Narrow hollow beam 602 reinforces the arm 105 and the two beams are connected at both ends of the arm (not shown). The hollowness of the rail structure is designed to reduce the weight of rail 106.

The arm 105 including the beams 602, 604 and the end piece 113 are made of plastic materials such as PTFE or other polymeric materials. The arm 105 may be manufactured by injection molding as one single piece.

7 Second Embodiment of the Impact Absorbing Gate

7.1 Overview

Referring to FIG. 8, a second embodiment of the impact absorbing gate 800 includes a first post assembly 802, a second post assembly 804, and a rail assembly 806 extending between the first post assembly 802 and the second post assembly 804.

The first post assembly 802 has a first cylindrical post body 806 with a first impact absorbing anchoring assembly 810 disposed at its distal end 811. A first rotatable bumper 814 is installed on the first post body 806 at a height where the first post assembly 802 is likely to be struck by, for example, stock handling equipment. Similarly, the second post assembly 804 has a second cylindrical post body 808 with a second impact absorbing anchoring assembly 812 disposed at its distal end 813. A second rotatable bumper 816 is installed on the second post body 808 at a height where the second post assembly 804 is likely to be struck.

In general, the first and second impact absorbing anchoring assemblies 810, 812 are configured to attach the first and second post assemblies 802, 804 to a surface 801 in a way that reduces a rigidity of the coupling between the surface 801 and the post assemblies 802, 804, as is described in greater detail below.

In some examples, the rotatable bumpers 814, 816 are formed from an elastic material and mitigate the effects of impacts on the post assemblies 802, 804 by (1) absorbing a force of the impact by deforming and (2) rotating to redirect (i.e., deflect) the force of the impact away from, and to the sides of the post assemblies 802, 804. In some examples, the rotatable bumpers 814, 816 rotate on a track (not shown) attached to (or formed on) the cylindrical post bodies 806, 808.

The first post assembly 802 includes a first opening 818 at its distal end 819 into which a first end 820 of the rail assembly 806 extends and the second post assembly 804 includes a second opening 822 at its distal end 821 into which a second end 824 of the rail assembly 806 extends. The first end 820 of the rail assembly 806 is attached to a bistable opening/closing mechanism (see FIG. 9) that (1) causes the gate to automatically move to a fully opened position when the gate is rotated past a threshold position and (2) causes the gate to automatically move to a fully closed position when the gate is rotated to less than the threshold position, as is described in greater detail below.

The second end 824 of the rail assembly 806 rests in a safety catch mechanism (see FIG. 9) in the second post assembly 802. As is described in greater detail below, the safety catch mechanism allows second end 824 of the rail assembly 806 to freely move (by rotation) into and out of the second opening 822 when the rail assembly 806 is not under a force of impact, but prevents movement of the second end 824 of the rail assembly 806 out of the second opening 822 when the rail assembly 806 is under a force of impact.

The rail assembly 806 includes an upper rail 807 and a lower rail 809, rotatably connected by coupling bars (see FIG. 9). A reinforcing cable (e.g., a nylon or steel cable, not shown) extends through the lower rail 809. In some examples, the lower rail 809 includes one or more handles 830 that are appropriately placed such that operators of the gate can grab the handles 830 to open or close the gate.

Referring to FIG. 9, when the outer surfaces of the elements of the impact absorbing gate are made transparent, the bistable opening/closing mechanism 926 in the first post assembly 802 becomes visible, as does the safety catch mechanism 928 in the second post assembly 804. The reinforcing cable 930 extending along an interior of the lower rail 809 of the rail assembly 806 is also visible.

7.2 Bistable Opening/Closing Mechanism

Referring to FIGS. 10 and 11, in some examples, the bistable opening/closing mechanism 926 includes a strut 932 and a linkage 934. The linkage 934 includes a series of two or more interconnected metal bars or rods and rotatably couples an end cap 936 at a first end 938 of the lower rail 809 to the post body 806 of the first post assembly (e.g., via a sleeve 940). The strut 932 attaches an intersection 942 of two of the metal bars or rods of the linkage 934 to a base plate 944 of the first impact absorbing anchoring assembly 810. The strut 934 includes a spring 946 and a shock absorber (positioned inside the spring and not shown).

Referring also to FIGS. 12 and 13, as is noted above, the combination of the linkage 934 and strut 932 is configured to cause bistable operation of the gate. For example, to open or close the gate, an operator rotates the rail assembly 806 about its first end 820, where the rail assembly 806 is rotated to 0° when the gate is fully closed and 90° when the gate is fully opened. Between 0° and 90° of rotation, there is a threshold angle, T°. If the operator rotates the rail assembly 806 to an angle less than or equal to T°, the configuration of the linkage 934 and strut 936 causes the strut 936 to compress and the rail assembly 806 to automatically return to the 0°, closed position. If the operator rotates the rail assembly 806 to an angle greater than T°, the configuration of the linkage 934 and strut 936 causes the strut to expand, and the rail assembly 806 to automatically move to the 90°, opened position. This bistable operation of the opening/closing mechanism 926 ensures that the gate does not remain partially opened, where people or equipment are prone to strike the rail assembly 806.

In some examples, installers of the gate may cut the rail assembly 806 to a shorter length (e.g., to accommodate openings of different sizes). Doing so will change the weight of the rail assembly and therefore change the value of the threshold angle, T°. The bistable opening/closing mechanism 926 is adjustable (e.g., by changing a tension on the spring 946 or adjusting lengths of the rods/bars in the linkage 934) so the installer can adjust the threshold angle, T° to account for the new length and weight of the rail assembly 806.

7.3 Safety Catch Mechanism

Referring to FIGS. 14 and 15, the safety catch mechanism 928 in the second post assembly 804 is implemented using one more catches 948 disposed in the second post assembly 804 and a pin 952 extending through a second end 950 of the lower rail 809. In some examples, each of the catches 948 includes a notch 956 with a sloped surface 958 and a stop surface 960.

When there is little or no force being applied to the lower rail 809, the pin 952 in the second end 950 of the lower rail 809 is positioned outside the notches 956 of the catches 948. The catches 948 therefore do not interfere with movement of the second end 824 of the rail assembly 806 into and out of the second opening 822 of the second post assembly 804 as the gate is opened and closed.

On the other hand, when sufficient force is applied to the lower rail 809 (e.g., by a fork truck striking the rail assembly 806), the pin 952 in the second end 950 of the lower rail 809 moves into one or both of the notches 956 (possibly guided by the sloped surface 958). With the pin 952 in one or both of the notches 956, any force applied to the rail assembly 806 that tends to cause the second end 824 of the rail assembly 806 to move out of the second opening 822 of the second post assembly 804 will cause the pin 952 to slide along the notches 956 until it contacts the stop surface(s) 960. When the pin 952 contacts the stop surface(s) 960, the second end 824 of the rail assembly 806 is prevented from moving any further out of the second opening 822 (i.e., preventing the gate from opening when struck).

When the force of an impact is removed from the lower rail 809, the pin 952 in the second end 950 of the lower rail 809 moves out of the notches 956 and the gate returns to normal operation.

7.4 Strap Retention Mechanism

Referring to FIG. 16, as was mentioned in the description of FIG. 9, in some examples, a reinforcing cable 930 extends along an interior of the lower rail 809 of the rail assembly 806. In some examples, the reinforcing cable 930 is a flat nylon strap that is attached to each end of the lower rail 809 using a strap retention mechanism 962. In some examples, the strap retention mechanism 962 operates in a similar fashion to the mechanism described in U.S. patent application Ser. No. 18/276,701, the entire contents of which are incorporated herein by reference. At the first end 938 of the lower rail 809, the nylon strap 930 is looped around a pivotable coupler 964 (similar to the pivotable coupler described above with reference to FIG. 4) about which the lower rail 809 rotates. A loose end of the nylon strap 930 is fed between two opposing surfaces of the strap retention mechanism 962 and fasteners 966 (e.g., bolts) are used to pinch and hold captive the loose end of the nylon strap between the two surfaces. A similar process is used to attach the nylon strap 930 to the pin 952 at the second end 950 of the lower rail 809.

7.5 Impact Absorbing Anchoring Assemblies

Referring to FIG. 17, the impact absorbing anchoring assemblies 810, 812 include a metal base plate 968 configured to fit inside two elastic covers 970 (only one of which is shown in the figure). When installed inside the elastic covers 970, the metal base plate rests on elastic material of the covers (i.e., is separated from the surface 801 by elastic material). Fasteners (e.g., bolts) are installed through openings 972 in the metal base plate 968 and corresponding openings 974 in the elastic covers 970 to secure the anchoring assemblies 810, 812 to the surface 801.

A number of embodiments of the invention have been described. Nevertheless, it is to be understood that the foregoing description is intended to illustrate and not to limit the scope of the invention, which is defined by the scope of the following claims. Accordingly, other embodiments are also within the scope of the following claims. For example, various modifications may be made without departing from the scope of the invention. Additionally, some of the steps described above may be order independent, and thus can be performed in an order different from that described.

Claims

1. An impact absorbing gate comprising: a first upright having a first proximal end attached to a surface and a first distal end;a second upright having a second proximal end attached to a surface and a second distal end;an arm having a first end and a second end, the first end being pivotably coupled to the first distal end of the first upright at a pivot point; anda bistable mechanism disposed in the first upright and configured cause the arm to rotate to a fully opened position when the arm is rotated to an angle in a first range of angles and to cause the arm to rotate to a fully closed position when the arm is rotated to an angle in a second range of angles.

2. The impact absorbing gate of claim 1 further comprising an impact absorbing pivotable coupling attaching the first end of the arm to the first distal end of the first upright, the impact absorbing pivotable coupling including: a hollow body extending through the first end of the arm;a bearing disposed within the hollow body, the bearing being rotatable relative to the hollow body;a resilient material disposed within the hollow body, anda fastener extending through the hollow body, the bearing, the resilient material, the first end of the arm, and the first distal end of the first upright,wherein the pivotable coupling is configured to permit movement of the arm with three degrees of freedom relative to the first upright.

3. The impact absorbing gate of claim 1 wherein: the second upright includes an opening and a catch disposed in the opening, the catch including a notch,the second end of the arm is configured to be received in the opening of the second upright and includes a pin configured to be received in the notch of the catch,wherein, in the absence of a predetermined amount of force being applied to the arm, the pin is not received in the notch of the catch such that the second end of the arm can freely move out of the opening of the second upright and, in the presence of the predetermined amount of force being applied to the arm, the pin is received in the notch such that the second end of the arm is prevented from moving out of the opening of the second upright.

4. The impact absorbing gate of claim 1 wherein one or both of the first upright and the second upright includes a rotatable bumper.

5. The impact absorbing gate of claim 4 wherein the rotatable bumper includes a cylindrical body configured to rest on and rotate about a cylindrical rail attached to the upright.

6. The impact absorbing gate of claim 1 further comprising a nylon strap extending through arm.

7. The impact absorbing gate of claim 6 further comprising pivotable coupling attaching the first end of the arm to the first distal end of the first upright, wherein the nylon strap has a loop disposed at its first end and a part of the pivotable coupling extends through the loop.

8. The impact absorbing gate of claim 7 wherein a second end of the nylon strap includes a second loop and the second end of the arm includes a pin, wherein the pin extends through the loop.

9. The impact absorbing gate of claim 1 wherein the bistable mechanism includes a spring, a strut, and a linkage.

10. The impact absorbing gate of claim 9 wherein the spring and the strut are arranged coaxially, with the strut inside the spring.

11. The impact absorbing gate of claim 10 wherein the first range of angles and the second range of angles are separated by a threshold angle.

12. The impact absorbing gate of claim 11 wherein the threshold angle is adjustable.

13. The impact absorbing gate of claim 12 wherein the threshold angle is adjustable by adjusting a tension in the spring.

14. The impact absorbing gate of claim 12 wherein the threshold angle is adjustable by adjusting a configuration of elements of the linkage.

15. The impact absorbing gate of claim 12 wherein the threshold angle is adjustable by adjusting the strut.

16. The impact absorbing gate of claim 12 wherein the first proximal end of the first upright is attached to the surface using a first impact absorbing anchoring assembly and the second proximal end of the second upright is attached to the surface using a second impact absorbing anchoring assembly.

17. The impact absorbing gate of claim 1 wherein the arm is coupled to the surface through the bistable mechanism.

18. The impact absorbing gate of claim 1 further comprising a second arm extending between the first and second uprights and rotatably coupled to the arm.

19. The impact absorbing gate of claim 1 wherein the opening in the second upright is tapered.

20. A gate comprising: a first post assembly;a second post assembly having an opening and a catch disposed in the opening, the catch including a notch;a rail assembly with a first end rotatably coupled to the first post assembly and a second end configured to be received in the opening of the second post assembly, the second end including a pin configured to be received in the notch of the catch;wherein, in the absence of a predetermined amount of force being applied to the rail assembly, the pin is not received in the notch of the catch such that the second end of the rail assembly can freely move out of the opening of the second post and, in the presence of the predetermined amount of force being applied to the rail assembly, the pin is received in the notch such that the second end of the rail assembly is prevented from moving out of the opening of the second post.