Land vehicles – Wheeled – Tiltable vehicles – stabilized by attendant or article
Reexamination Certificate
2000-03-08
2001-05-08
Johnson, Brian L. (Department: 3618)
Land vehicles
Wheeled
Tiltable vehicles, stabilized by attendant or article
C280S047240, C280S043120, C280S043140, C280S047200, C280S047190, C280S759000, C414S673000, C182S013000, C182S016000
Reexamination Certificate
active
06227553
ABSTRACT:
FIELD OF THE INVENTION
This invention provides an attachment assembly adapted for use by roofers during installation or repair on a flat roof, or an equivalent roof-like surface of a structure, the assembly providing, for example, for the attachment thereto of a safety harness or harnesses as worn by a person or persons respectively working on the roof The assembly may be used alone, or may be adapted for mounting on a wheeled utility cart such as is commonly used by roofers to move materials on the roof surface, or may be provided as an integral part of such a cart.
REVIEW OF THE PRIOR ART
It is an increasing requirement when persons work on high above ground roof or roof-like surfaces of various structures, for example for the purpose of installation, maintenance and repair, to provide against the possibility of accidental falls to the ground below. Since a fall of quite a short distance can cause serious injury, or even death, the provision of such safety means is desirable when the height of the surface above the ground is as small as about 2 meters (6 feet), and some jurisdictions now require a safety installation of some kind for all work above this height. One type of structure with which such a safety installation is particularly necessary is a flat building roof, since these are always well above the minimum height and usually have only a low parapet rising to about knee-height extending around the outside edge, such a parapet usually also having a number of breaks and gaps around its perimeter. Other instances in which some provision must be made for safety on a roof surface is when skylights are being installed or repaired, or when an entire section of roof has been removed to replace the underlying roofing beams and rafters, both examples involving the creation of a dangerous open space on the roof. Yet another instance are the open floors of a multi-storey building before the outside curtain walls have been installed. One safety arrangement consists of guard rails that are attached to the structure so as to surround the area in which the operatives are working, and are preferred if possible since the operatives can move freely over the area, but they are relatively expensive and usually can only be justified economically when the area is large and/or the work will take an extended period of time to complete. A less expensive installation comprises a safety harness worn by each worker that is releasably attached by a tether line and snap hook or shackle to a secure attachment point on the structure. Such a secure point or points must of course be strong enough to withstand the forces applied thereto by a falling body, or in a worst case scenario to withstand the forces applied thereto if all of the workers attached thereto fall simultaneously from the roof. It is usually extremely difficult to find existing attachment points that are suitable, especially on structures that were built before such a requirement was envisaged, and there is therefore the need for an assembly providing such a point that can readily be brought to the structure as and when required, and preferably also readily removed when the job is finished so that it can be used elsewhere.
A particular problem with flat roofs, or their equivalents, of any substantial size follows from the need to use tether lines that are long enough not to obstruct free movement over a usefully large enough area of the surface, while short enough to ensure that a falling body does not reach the ground. With a large roof this either involves providing a number of suitably spaced and located attachment points, or providing some means of moving the attachment point or points that are provided as the workers move over the roof surface. A standard piece of equipment for a roofer when operating on a flat roof is a so-called utility cart, which is a three or four wheeled cart (the third wheel, or one pair of the wheels, trailing and pivoting for steering purposes) which is small enough to be hoisted on to the roof by the usual temporary hoist or elevator, and which is then used to move supplies of roofing felt, asphalt, gravel, etc. over the roof. Such a utility cart is itself much too light to serve as an attachment point and, in view of the surprisingly high forces likely to be encountered in the worst case scenario of, say, three workers each weighing as much as 100 Kg (220 lbs) falling together from the roof surface, it becomes difficult if not impossible to load the cart sufficiently with dead weight, since this could require as much as about one metric ton, an amount which such utility carts are not usually designed to carry.
SUMMARY OF THE INVENTION
It is a principal object of the invention therefore to provide an attachment assembly structure usable as a free-standing structure on a flat roof surface and providing, for example, a secure attachment point for at least one, and preferably for as many as three safety harnesses, but which nevertheless can be moved about the roof relatively easily as required to permit the workers to work on different parts of the roof.
It is another object to provide an attachment assembly structure adapted for ready attachment to a wheeled utility cart as and when required, and when so attached providing a secure attachment point for, for example, at least one, and preferably as many as three safety harnesses, and which can nevertheless can be moved about the roof as required on the cart.
It is a further object to provide such an attachment assembly as an integral part of a wheeled utility cart structure of size such that it can readily be hoisted on to a roof and function as a secure attachment point for, for example, one or more safety harnesses.
In accordance with the invention there is provided an attachment assembly for use on a horizontal surface, the assembly when mounted on such a surface providing an attachment point for at least one safety harness permitting movement of a worker wearing the harness on the surface, the attachment assembly comprising:
an assembly base frame having a first side which in operation faces toward a surface edge over which a worker may fall, and a second opposite side facing away from that surface edge;
at least two surface engaging members mounted on the base frame at or adjacent to the first side and spaced longitudinally from one another along that first side, each surface engaging member having an upper and a lower end and each being attached to the base frame so that when the assembly is in position on a surface the respective lower end is in an operative position contacting or in close proximity to the surface between the first side and the surface edge; and
an attachment member carried by the base frame and providing an attachment point between the at least two surface engaging members;
a counterweight providing a counterweight moment and mounted on the assembly base frame so as to be disposed at the base frame second side;
whereby the application of a tension force to the attachment member in a direction having a component toward the surface edge urges the base frame to tilt toward the first side and thereby positively engage the surface engaging members lower ends with the surface, whereupon the thus engaged lower ends become pivots about which the base frame is urged by the tension force to pivot and thereby urge the counterweight upward away from the surface against its downward acting counterweight moment.
Also in accordance with the invention there is provided an attachment assembly for use on a horizontal surface, the assembly being adapted for attachment to a wheeled utility cart movable over the horizontal surface, the cart having a cart frame which has a first side thereof which in operation faces toward a surface edge over which a worker may fall, and a second opposite side facing away from that surface edge, and the assembly when so attached to the cart providing an attachment point for at least one safety harness tether line permitting movement of a worker wearing the harness on the surface, the attachment assembly comprising:
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Johnson Brian L.
Rogers Stanley J.
Sliteris Joselynn Y.
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