U.S. patent application number 11/295114 was filed with the patent office on 2007-06-21 for anti-spin/anti-drift worm gear brake with bevel gear speed-up.
Invention is credited to Edward A. Bell.
Application Number | 20070137518 11/295114 |
Document ID | / |
Family ID | 38171934 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070137518 |
Kind Code |
A1 |
Bell; Edward A. |
June 21, 2007 |
Anti-spin/anti-drift worm gear brake with bevel gear speed-up
Abstract
An anti-spin, anti-drift assembly for installation on a railroad
car plug-type door locking mechanism of the type having a gear
segment rotatably mounted on the door, rotatable pipes mounted on
the plug-type door, rods pivotally connected to the gear segment
and to the rotatable pipes so that rotation of the gear segment
brings about rotation of the pipes and opening and closing of the
plug-type door. The anti-spin, anti-drift assembly includes a worm
gear meshing with the gear segment. A speed up gear is located at
one end of the worm gear. A drive gear meshes with the speed up
gear and an operating wheel rotates the drive gear.
Inventors: |
Bell; Edward A.;
(Chesterton, IN) |
Correspondence
Address: |
Edward M. Keating;Cook, Alex, McFarron, Manzo,
Cummings & Mehler, Ltd.
200 W. Adams Street - Suite 2850
Chicago
IL
60606
US
|
Family ID: |
38171934 |
Appl. No.: |
11/295114 |
Filed: |
December 6, 2005 |
Current U.S.
Class: |
105/378 |
Current CPC
Class: |
E05B 83/02 20130101 |
Class at
Publication: |
105/378 |
International
Class: |
B61D 17/00 20060101
B61D017/00 |
Claims
1. An anti-spin, anti-drift assembly for installation on a railroad
car plug-type door locking mechanism of the type having a gear
segment rotatably mounted on said plug-type door, rotatable pipes
mounted on said plug-type door, rods pivotally connected to said
gear segment and said rotatable pipes so that rotation of said gear
segment brings about rotation of said pipes and opening and closing
of said plug-type door, the improvement comprising: a worm gear
meshing with said gear segment, a speed up gear at one end of said
worm gear, a drive gear meshing with said speed up gear, and an
operating member to rotate said drive gear.
2. The anti-spin, anti-drift assembly of claim 1 in which said
drive gear and said speed up gear form a bevel gear set.
3. The anti-spin, anti-drift assembly of claim 1 in which said worm
gear is a single lead thread.
4. An anti-spin, anti-drift mechanism for a rotatable gear segment,
said mechanism including: a worm gear meshing with said rotatable
gear segment, an operating member rotatably mounted relative to
said rotatable gear segment, and a bevel gear set operatively
connecting said operating member and said worm gear.
5. The anti-spin, anti-drift mechanism of claim 4 in which said
bevel gear set includes a speed-up gear at one end of said worm
gear and a drive gear connected to said operating member.
6. The anti-spin, anti-drift mechanism of claim 5 in which said
speed-up gear is a bevel gear.
7. The anti-spin, anti-drift mechanism of claim 6 in which said
bevel gear is formed integrally with said worm gear.
8. The anti-spin, anti-drift assembly of claim 3 in which said worm
gear is formed with a lead angle of said single lead thread having
a tangent which is greater than the coefficient of friction of the
engaging surfaces of said gear segment and said worm gear.
9. The anti-spin, anti-drift assembly of claim 4 in which said worm
gear is formed with a thread lead angle having a tangent which is
greater than the coefficient of friction of the engaging surfaces
of said gear segment and said worm gear.
Description
BACKGROUND OF THE INVENTION
[0001] Compression-sealing "plug-type" doors are provided for
railway freight cars of the type in which ambient sealing of the
interior is required. The closing and locking mechanisms for these
type of doors have consisted of cranks depending from pairs of
pipes rotationally secured to the doors and hand operated gear
mechanisms to rotate the pipes and cranks between open and closed
positions. Upon rotation of the pipes in a direction to apply a
closing force to the plug-type door, a gasket in the door frame is
usually compressed to seal the door. When the door is released, the
cranks rotate in a direction which moves the door laterally
outwardly so that it will clear the door frame for longitudinal
movement along tracks or rails attached to the car above and below
the door. Operating mechanisms of this type are powerful and when
the door is compressedly sealed, a reverse torque is imparted to
the operating handle or wheel as a result of the compression
forces. A reverse torque can also arise from other factors such as
load shifting inside the car which leans against the door or the
force of the door's own weight when the car is tilted to lean
outwardly. Operating mechanisms such as handles and wheels are
routinely secured against counter-rotation in the door-opening
direction by locking mechanisms of various types. However, to open
a door, the handle or wheel lock must be released. If during
rotation of the handle or wheel in the door-opening direction, the
operator loses control of the handle or wheel, the handle or wheel
will frequently spin, resulting in a highly dangerous condition to
the operator and anyone else nearby. The drive mechanisms for the
plug-type door opening and closing mechanisms include a gear
segment mounted on a bearing plate attached to the plug-type door.
Link rods connect the gear segment to the previously mentioned
rotatable pipes. The gear segment is rotated by a gear or gears
connected to the operating handle or wheel.
SUMMARY OF THE INVENTION
[0002] An anti-spin/anti-drift drive mechanism is provided which
can be installed in a conventional opening and closing mechanism of
a plug-type door to utilize the convention gear segment of this
mechanism.
[0003] An object of this invention is a anti-spin/anti-drift drive
mechanism which utilizes the self locking characteristics of a
properly designed worm gear to prevent spinning and drifting of a
plug-type door.
[0004] Another object of this invention is a drive mechanism using
a worm gear with a speed up to overcome the large speed reduction
of the worm gear so that a plug-type door can be opened with the
same number of rotations of the operating handle or wheel that the
current spur gear designs provide.
[0005] Other objects will be found in the following specification,
drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The invention is illustrated more or less diagrammatically
in the following drawings wherein;
[0007] FIG. 1 is a partial front elevational view of the mechanism
of this invention with some parts omitted and other broken away for
clarity of illustration and showing the mechanism in a door closed
position;
[0008] FIG. 2 is a view similar to that of FIG. 1 but showing the
mechanism in its door opened position;
[0009] FIG. 3 is an exploded view of the mechanism of FIGS. 1 and 2
with parts omitted for clarity of illustration, and;
[0010] FIG. 4 is a partial enlarged view of the meshing of the
gears of the bevel gear set.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0011] This invention is concerned with an anti-spin/anti-drift
drive for the operating mechanism of a door of a railroad car,
particularly a plug-type door. Both anti-spin/anti-drift drives and
operating mechanisms for plug-type doors are well known in the
railroad industry and examples of both are shown in U.S. Pat. No.
3,555,731 (Ross, Jr.) and U.S. Pat. No. 4,920,894 (Thoman), both of
which patents are incorporated herein by reference for all
purposes.
[0012] Referring now to the figures of the drawings, an outline of
a plug-type door 11 (FIG. 3) is shown with a bearing plate 13
attached thereto in a conventional manner. A conventional door
opening and closing mechanism 15 includes a gear segment 17 which
is pivotally mounted on the bearing plate 13 by a shaft 19 (FIG.
3). Link rods 21 are pivotally connected to the gear segment 17 and
are connected to rotatable pipes 23, only one of which is shown in
FIGS. 1 and 2 of the drawings, which open and close the plug-type
door 11 as described in U.S. Pat. No. 3,555,731 and U.S. Pat. No.
4,920,894. In the preferred form of the invention, the worm gear
25, its shaft 31 and the bevel gear 45 are integrally cast of
ductile iron.
[0013] In this invention, the anti-spin/anti-drift mechanism
includes a worm gear 25 having a single lead thread 27 which meshes
with the teeth 29 of the gear segment 17. The worm gear includes a
shaft 31 having sleeve bearings 33 and 35 which are journalled in
mounting pillow blocks 37 and 39 fastened to the bearing plate 13.
In this embodiment of the invention, the mounting pillow block 37
is permanently attached to the bearing plate 13 such as by welding.
The mounting pillow block 39 is removably fastened to a base block
41 by removable threaded fasteners 43 with the base block
permanently fastened to the bearing plate 13 as by welding. The
provision of the removable mounting pillow block 39 permits the
installation of the worm gear 25 in a conventional existing door
opening and closing mechanism without a complete disassembly
thereof. A bevel gear 45 is formed at one end of the worm gear 31.
The bevel gear may be cast as an integral part of the worm gear and
functions as a speed up gear to overcome the large speed reduction
of the worm gear. In the preferred form of the invention, the worm
gear 25, its shaft 31 and the bevel gear 45 are integrally cast of
ductile iron.
[0014] The bevel gear 45 is part of a bevel gear set which includes
a face gear 47 having axially extending teeth 49 that mesh with the
teeth 51 of the bevel gear 45. The face gear 47 is mounted on a
shaft 53 which is journalled in the bearing plate 13 at one end and
is fastened at the opposite end of the shaft 53 to an operating
member such as a wheel 55, although a conventional handle may also
be used. A cover plate is located between the face gear 47 and the
wheel 55, but has been omitted from the drawings for clarity of
illustration. The wheel 55 is formed with a raised hex head hub 57
to permit the use of a power driven wrench to operate the
wheel.
[0015] The provision of a worm gear 25 meshing with the teeth 29 of
the gear segment 17 provides the locking friction to prevent
unintended rotation of the operating wheel 55 whether the plug-type
door is in its closed position or in being moving along the side of
a railroad car in its open position. The self locking result is
obtained when the worm thread is formed so that the tangent of the
lead angle of the worm thread is greater than the coefficient of
friction of the engaging surfaces of the gear segment 17 and the
worm gear 25. For example, if the gear segment 17 and the worm gear
25 are cast of ductile iron, the lead angle of the worm thread is
formed as 3.5 degrees. The tangent of the lead angle is 0.62. The
coefficient of friction of the engaging surfaces of cast iron gear
segment 17 and the worm gear 25 is 0.12. In accordance with the
aforementioned formula, self-locking of the worm gear is achieved.
For other materials having different coefficients of friction, the
lead angle of the worm gear must be varied in accordance with the
aforementioned formula to achieve self-locking.
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