Fire escape – ladder – or scaffold – Safety device for ground-supported ladder
Utility Patent
1999-07-23
2001-01-02
Chin-Shue, Alvin (Department: 3634)
Fire escape, ladder, or scaffold
Safety device for ground-supported ladder
C182S206000, C182S129000
Utility Patent
active
06167988
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to ladder stabilizers and more specifically to a stabilizer for a lineman's ladder which will position a workman at a comfortable and efficient working distance from utility pole mounted devices, including electrical equipment cabinets, and moreover will complete a four-point support for the lineman's ladder, thereby improving stability and safety.
BACKGROUND OF THE INVENTION
In order to understand the prior practices and techniques to access and service utility pole mounted equipment cabinets it is best to refer to FIG.
1
. Ladder
10
is illustrated engaging a messenger cable
12
that is supported on a utility pole
14
. Aerially installed telephone cable
16
typically is supported or suspended on a utility pole
14
by a messenger cable
12
.
Similarly, aerially installed cable television cable
20
is suspended on utility pole
14
, and messenger cable
12
provides the support for the television cable
20
.
Typically, the messenger cable
12
is attached to the utility pole
14
by a clamp
22
or equivalent which, in turn, is bolted to utility pole
14
. The telephone or cable television cable
16
,
20
then is lashed to the messenger cable
12
with lashing wire
24
.
Telephone linemen and cable television linemen have used a ladder which has become known as a telephone lineman's or lineman's ladder
10
. The ladder
10
comprises a pair of parallel side rails
26
and a plurality of rungs
28
transverse to and joining the rails
26
.
At one end of side rails
26
of ladder
10
, a pair of hooks
30
are installed on and attached, extending beyond the end of the rails
26
. The hooks
30
may be used to hook over a messenger cable
12
to support the ladder
10
, either at a utility pole
14
or at a mid-span location between utility poles
14
; thus the upper end of ladder
10
hangs on and is supported from the messenger cable
12
. This engagement prevents the upper end of the ladder
10
from sliding off the messenger cable
12
and creates a four-point support for the ladder
10
.
The hooks
30
are a major contributing factor in stabilizing the lineman's ladder
10
. Previously, such a ladder
10
could be leaned against a pole or the messenger cable creating an unstable three-point support for the ladder
10
leaning against the utility pole
14
or a four-point support at a pole
14
or at a mid-span location that is exposed to the ladder
10
shifting or slipping laterally relative to the messenger cable
12
under the weight of the lineman, and possibly collapsing. The use of the hooks
30
permits a lineman to ascend the ladder
10
and be positioned at a reasonably comfortable working distance from the messenger cable
12
and the telephone/cable television cables
16
,
20
when standing on a rung high enough to place the cables
12
,
16
,
20
approximately chest high.
However, when an electrical equipment cabinet
50
or box
50
is installed on a utility pole
14
as shown in
FIG. 2
, the lineman's ladder
10
is positioned too far under cabinet
50
for the lineman to be able to work within cabinet
50
comfortably and safely. Electrical equipment cabinet
50
typically contains electronic equipment such as repeaters, amplifiers, fiber-optic cable-to-copper cable converters, all of which must be protected from the elements and which must be serviced from time to time. Typically, access to the equipment within cabinet
50
is through the front face
52
by opening doors
54
. Sufficient room between the lineman and the cabinet
50
must be allowed to open the doors
54
without the lineman having to avoid the swinging of door
54
and possibly losing his balance.
Efforts to stabilize ladders relative to utility poles or trees have been made in the past. Examples of the these efforts include: U.S. Pat. Nos. 631,302; 2,432,189; 3,792,756; 4,379,498; 4,440,263; and 4,823,911.
U.S. Pat. No. 631,302 discloses an attaching device for attaching and supporting a ladder on a telephone pole. The ladder is disposed parallel to the pole and relies on a pole grip and a clamp to attach the ladder. The parallel position of the ladder relative to the utility pole creates a rise substantially vertically relative to the ground. The ladder's vertical orientation makes working from it without a safety belt extremely difficult, and working within a pole mounted equipment cabinet becomes virtually impossible.
U.S. Pat. No. 2,432,189 discloses a bracket attached to the rungs of a ladder to engage a sloping roof surface to cause the ladder to stand-off from the eaves of the roof, preventing damage to the eave parts.
U.S. Pat. No. 3,792,756 discloses a safety strap arrangement to encircle a utility pole, thereby preventing slippage of the ladder in a lateral direction and attempting to stabilize a three-point support for the ladder. This arrangement fails to address the possibility of a ladder pivoting about the single point of support on the pole and causing the person on the ladder to be shifted and fall off the ladder.
U.S. Pat. No. 4,379,498 describes a safety device for a ladder comprising a partially cylindrical member attached to a rung or similar crossbar extending between the side rails of the ladder. The partial cylindrical member is vertically oriented in use and is provided with toothed edges for engaging a tree trunk to improve stability of the ladder. While a four-point support arrangement, the device is still subject to twisting and causing a fourth point of support to disengage from the tree.
U.S. Pat. No. 4,440,263 discloses a ladder attachment that spans a distance substantially wider than the ladder to engage the side walls of a building on either side of a window or similar opening, thus preventing the ladder from engaging and damaging the window proper.
U.S. Pat. No. 4,823,911 illustrates a hook supported crossbar for supporting a scaffold on a ladder. The hook engages a ladder rung and the crossbar includes members on the ends of the crossbar to prevent the scaffold from sliding off the end of the crossbar.
None of the foregoing patents address the need to position a workman away from a utility pole, on a ladder to work safely and efficiently on equipment mounted on the utility pole while providing a stable four-point support for the ladder.
OBJECTS OF THE INVENTION
It is an object of the invention to stabilize a lineman's ladder with a four point support.
It is another object of the invention to provide a stand-off for the lineman's ladder to thereby space the ladder from the utility pole or other stable structure.
It is a further object of the invention to enable a workman on a lineman's ladder to assume working position within convenient reach of equipment within an enclosure mounted on a utility pole at approximately the level of the messenger cable.
SUMMARY OF THE INVENTION
The shortcomings of the prior art are overcome and the objects of the invention are carried out by a lineman's ladder stabilizer and support which mounts on a utility pole. The mount for the stabilizer is a sheet metal member formed in a compound “U”-channel shape. The primary U-channel has a bottom segment which is further formed to create a secondary channel. The secondary channel is shaped in a truncated wedge shape to accept a portion of a utility pole and engage the utility pole with the edges of the secondary channel. The side walls of the primary channel extend outwardly from the pole to support an electrical equipment cabinet or enclosure. The mount itself is rigidly bolted to the utility pole at the desired elevation.
The mount may be used to attach the stabilizer to the wall of a building, a tower, trestle or pole of various materials.
Extending from the mount, outwardly and preferably downwardly, is a projecting support arm. At a distal end of the projecting support arm is a horizontally disposed rigid cross-member. The cross-member is thus displaced from the utility pole. The cross-member is equipped with flange plates of a larger dimension than the diameter of th
Frodge David Bruce
Vogt James
Chin-Shue Alvin
Letson Lawrence R.
Moore Diversified Products
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