Exhaust stack stopper

A device is disclosed for shutting off the flow of exhaust gases from the exhaust outlet of a diesel engine having a substantially vertical exhaust stack. The device is especially useful for stopping the flow from one of twin diesel stacks when a tractor or truck having twin stacks from a single manifold is undergoing maintenance in an indoor facility. The device permits an operator standing on the floor to position a resilient pad in sealing engagement with a stack outlet twelve feet or more above floor level and lock the pad into position and to remove the device, again from ground level, when maintenance has been completed and the engine shut down.

This invention relates generally to improving air quality in the workplace, 
and more particularly to facilitating the removal of exhaust fumes from 
shops where diesel trucks and tractors are maintained. 
In the trucking industry many diesel-powered vehicles are equipped with 
twin vertical exhaust stacks, one on the left side of the driver's cab and 
one on the right, with both leading from a single engine manifold. While 
this symmetrical arrangement may be more pleasing aesthetically, when the 
time comes for maintenance or overhaul it presents a problem. Typically 
each service bay for diesel vehicle maintenance is equipped with a single 
hose drop for carrying exhaust fumes to a duct system for transfer out of 
the building. For proper control of emissions, twin stack vehicles require 
duplication of the usual equipment--two exhaust canes, two nozzles, two 
flexible hoses, and two connectors to the duct system. This duplication of 
equipment is not always available or practicable, with the result that the 
twin stack vehicle may be fitted with only one exhaust removal arrangement 
in the vain hope that the pressure drop caused by the single removal 
system will remove substantially all of the exhaust fumes. The result, of 
course, is unacceptable levels of exhaust fumes being vented into the 
building. 
The present invention provides a device that is capable of stopping the 
flow of exhaust fumes from one of the twin stacks so that all the engine 
emissions may be taken into a single exhaust removal system. The invention 
recognizes that there are different configurations of the outlet of 
exhaust stacks and provides for dealing with a variety of outlet 
arrangements. Essentially, the device provides a means for an operator 
standing on the floor of the maintenance facility to close off one of the 
twin stacks, even though the stack outlet may be twelve feet or more above 
floor level. Once fixed in place, the device remains in place, unattended, 
to be removed when the maintenance procedures have been completed and the 
engine shut down. 
The device consists of a plate to which is affixed a heat-resistant, 
resilient pad, positioning means for holding the plate, and means for 
applying to the positioning means a downward force that holds the pad in 
sealing engagement with the exhaust stack outlet. The structure of the 
positioning means and the manner in which it holds the plate will vary 
with the conformation of the stack outlet, i.e., whether the plane of the 
outlet is horizontal, vertical, or at an angle. For example, the 
positioning means may be a yoke in which the plate can pivot or a frame 
holding the plate. In one embodiment the downward force will be applied to 
the positioning means by an appropriate weight, and the positioning means 
can be placed on top of the stack in any convenient manner, such as 
lowered from above or placed from the floor by means of the releasable 
clamp on a pole. In another embodiment the positioning means may be 
mounted on a support member, with the downward force applied to the 
support member. The height of the positioning means on the support member 
may be adjustable. Means are provided for adjusting the plane of the plate 
to be parallel to the plane of the exhaust stack outlet and locking it in 
that position. Also provided are means for aligning and maintaining the 
plate opposite to and in close proximity with the outlet, with the pad 
facing the outlet. When a support member adapted to place the device on 
the stack from the floor is used, on the lower portion of the support 
member may be mounted a yoke. (As used in describing the present 
invention, a yoke is roughly Y-shaped and consists of a U-shaped member 
and a stem. The cross section of the U-shaped member may be a smooth 
curve, such as a semicircle, or be made up of straight segments, such as a 
flattened U or a section of a polygon. The U-shaped member has a center 
portion, two end portions, a concave side, and a convex side. The stem has 
two ends, one attached to the center portion of convex side of the 
U-shaped member; the other end may be referred to as the free end.) In one 
use, the concave side of the yoke is designed to rest against the heat 
shield of the stack, or the lower portion of the stack if there is no heat 
shield, while the free end of the stem is adjustably mounted on the 
support member in such a way that the distance between the heat shield or 
stack and the support member may be adjusted and locked in place. The 
smaller diameter of an exhaust stack requires a yoke different in size 
from that used on a heat shield. The design of the device permits rapid 
replacement of a yoke of one size with a yoke of a different size. (It is 
understood that alternative configurations to yokes, having the same 
effect, may be substituted.) The downward force may be applied to the 
support member by means of a weight or by attachment to the heat shield or 
the tractor body by tensioning means.

Referring now to FIG. 1, there is shown in section a vehicle cab, indicated 
generally at 11, having an engine exhaust manifold 12 that is split into 
two exhaust stacks 13 and 14 with elbow turn-outs, each having a heat 
shield 15. (As noted above and illustrated in FIG. 8, the presence of a 
heat shield is not needed for the use of the device of the invention.) In 
FIG. 1 a device of the invention has been applied so that no exhaust gases 
flow through stack 14. (Some diesel vehicles have shorter stacks, as shown 
by 14A.) All engine fumes flow through stack 13, are captured by exhaust 
cane 16, and are carried to the building exhaust duct system through 
flexible hose 18, which is attached to the exhaust cane by nozzle 17. In 
the embodiment of the invention shown, heat-resistant resilient pad 19 is 
mounted on plate 20, which is attached to the positioning guide 21, and 
this assembly, more fully depicted in FIGS. 2, 3, and 4, is mounted on the 
upper portion of support member 22. Yoke 23, more fully depicted in FIG. 
5, is mounted on the lower portion of support member 22. In this 
depiction, two stretch tension straps 24, only one of which can be seen, 
have one end fastened to support member 22 and the other end, under 
tension, hooked to the bottom edge of heat shield 15 to supply a downward 
and inward (toward the stack) force that places the pad 19 in sealing 
engagement with the exhaust stack outlet. In the embodiment shown in FIG. 
2 the plate and guide assembly is adjustably mounted on the support member 
so that one device of this design can be used to stopper exhaust stacks of 
different heights. 
The plate and guide assembly of the design of FIG. 1 is shown in more 
detail in FIG. 2, where the elbow contour bar 25 and the arch 26, which 
make up positioning guide 21 of FIG. 1, can be seen to aid in positioning 
pad 19 laterally relative to the stack outlet, as well as allowing the 
adjustment at the ends of the arch to conform the elbow contour bar to the 
configuration of the stack turn-out. Adjustable locking means 27, which 
secures the guide position for adjustment to a particular stack elbow 
curvature, is more fully depicted in FIG. 3. Tube 28, mounted on the 
opposite side of plate 20 from the pad and free to slide up and down 
support member 22, shows one way the plate and guide assembly may be 
adjusted to stack outlets of different heights. Tabs 34, mounted on the 
plate, afford one way to attach the assembly to support member 22 or tube 
28. Adjustable locking device 29, for example, a cam-twist or 
drill-through and pin, shows how the vertical position of the plate and 
guide assembly may be locked in place at the desired height on the support 
member. 
One preferred embodiment of plate and guide assembly, which is particularly 
adapted to use on exhaust stacks having a curved or angled turn-out and 
for which the plane of the exhaust outlet is nominally vertical, is shown 
in FIG. 3. Here the resilient pad 19 is held onto plate 20 by means of a 
retainer 30, attached to the plate with fasteners 31. Side guides 32, 
attached to plate 20 by fasteners 33, insure that the plate and 
positioning means assembly is properly positioned with regard to the stack 
outlet. Elbow contour bar 25 is affixed to the upper portion of plate 20 
and to the center of U-shaped member 26 with fasteners 35. (The cross 
section of the U-shaped member may vary as described above for the 
U-shaped member of a yoke.) The free ends of the U-shaped member contain 
slots 36 through which extend threaded studs 37, which may be mounted on 
an angle bend of a portion of the plate or on angled tabs affixed to the 
plate. Wing nuts 38 screw on the studs 37. The U-shaped member may be 
moved within the constraints of the slots so that the distance between the 
elbow contour bar and the plate may be adjusted according to the curvature 
of the stack elbow turn-out, and fixed in place when the wing nuts are 
tightened. Also shown on FIG. 3 are wire shims 39, mounted between the 
plate and the upper portion of the pad. The shims serve to keep the pad in 
sealing engagement with the stack outlet when the downward and inward 
force tends to pull the pad away from the top of the stack outlet. The top 
of the pad may be held in place by the elbow contour bar, as shown. 
FIG. 4 is a plan view of the assembly shown in FIG. 3. The shims 39 are 
seen to be curved to conform at least roughly to the curvature of the top 
of the stack outlet so as to raise the pad to seat firmly against the 
stack outlet. 
FIG. 5 depicts the lower portion of the embodiment shown in FIG. 1. Tube 40 
extends through support member 22 permitting the stem portion 41 of yoke 
23 to move back and forth through the support member. Bracket 42, which is 
affixed to support member 22 and is in a plane nominally tangent to the 
curvature of the heat shield, has two holes, one on each side of support 
member 22. The two stretch-tension hold-down straps 24 have an S-hook 43 
at each end, one S-hook passing through one of the holes in bracket 42 and 
the S-hook at the other end of the strap hooked under the bottom edge of 
the heat shield. The straps are under tension so as to apply a downward 
and inward force to the support member, forcing the resilient pad against 
the stack outlet in sealing engagement. Alternative methods for securing 
support member 22 at a selected distance from the heat shield by locking 
stem 41 in position relative to tube 40 are pin 44, which passes through 
the tube and through the appropriate one of a series of holes in the stem, 
and lock-set device 45 for locking the position of the stem in the tube. 
Grips 46 are for the convenience, protection, and comfort of the operator. 
In operation the device will usually be put in place before the engine is 
started. The operator, having first set the appropriate adjustment for the 
stack elbow curvature, will bring the pad and positioning means assembly 
down over the top of the exhaust stack outlet so that the pad is adjacent 
to the stack outlet, fasten the tension straps in position, and then 
adjust the distance of the yoke from the center line of the stack so as to 
press the pad into sealing engagement with the stack outlet. When the 
engine is started, the operator can check to see whether there is any 
leakage of exhaust, and if so, adjust the yoke position to eliminate the 
leak. 
FIG. 6 shows a different preferred embodiment particularly adapted to 
exhaust stacks having a vertical discharge rather than a turn-out. In FIG. 
6 support member 47, which is not offset as is the support member of FIG. 
1, has at the lower portion a yoke arrangement similar to that described 
for FIG. 5. The upper portion has a stem-mounted guide ring 48, which 
encircles the curvature of the exhaust stack, the stem end of which is 
attached to the support member to keep the support member at a fixed 
distance from the stack. The upper portion of the support member above the 
guide ring is angled toward the stack and ends in a second yoke 49, which 
is positioned with one end of the open portion on either side of the 
exhaust stack. Near the two ends of the open end of yoke 49 are pivot 
holes 50 adapted to be placed over the center line of the exhaust opening. 
Plate 51, on which is mounted heat-resistant, resilient pad 52, is 
arranged to pivot on an axle that passes through pivot holes 50, as is 
more clearly shown in FIG. 7. 
FIG. 6A shows a variation of the positioning means of FIG. 6 in which the 
stem of yoke 49, or an extension of the stem, is attached to the guide 
ring 48 on the side opposite the attachment of the ring to support member 
47. Either the device of FIG. 6 or the variation of FIG. 6A can be used to 
stop the flow from a flat cut or slant cut outlet. The clearance between 
the exhaust stack and the tractor cab, as well as the direction of a slant 
cut outlet, will determine if it is more convenient to use a device with 
the positioning means on the same side as the support member or on the 
opposite side. 
FIG. 7 shows in greater detail the upper portion of the embodiment of FIG. 
6. Axle 54 is attached to plate 51 by mountings 53 and passes through the 
pivot holes 50, ending at one or both ends in a threaded portion on which 
a wing nut 55 may be tightened to provide sufficient resistance to the 
rotation of the plate to keep it from moving freely, but not so much that 
the pad will not seat firmly on the stack outlet when a downward force is 
applied. 
FIG. 7A shows a different manner of adjustably mounting plate 51. Here the 
U-shaped member of the yoke has been replaced with a rectangular member 
56. A ball and socket joint 57 is mounted on the back of plate 51, with 
the stem of the joint fastened to the rectangular member by mounting 58. 
The manner of mounting the pad on the plate is not shown. A variety of 
possibilities will be evident to those skilled in the art, including high 
temperature cement, a retaining frame fastened to the plate, or direct 
attachment with any appropriate fasteners. 
FIG. 8 shows the device with the modification of FIG. 6A in use on an 
exhaust stack without a heat shield, with a tractor cab and body 59 shown 
in outline. The device of FIG. 8 requires the substitution of a different 
size yoke 23 to conform to the difference in diameter between the heat 
shield and the exhaust stack. In FIG. 8 the tension straps 24 are hooked 
at their lower ends to metal step 60, which is above fuel tank 61. 
Regardless of how the stack is mounted relative to the cab, there will be 
available some suitable point of attachment for the lower end of the 
tension straps or other tensioning means. 
FIG. 9 shows an embodiment of the device especially adapted for use on 
stacks having a rain cap, but also having features that may be used with 
other embodiments. The rain cap assembly, made up of rain cap 58 and 
counterbalance 59, is free to pivot about pivot point 60 of mounting strap 
61. The mounting strap is secured at or near the top of the stack with 
bolt 62. The pad-holding plate and yoke assembly for a stack with a rain 
cap may be essentially as shown in FIG. 7o However, as shown in FIG. 9 
plate 63 has a cutout portion at one end to accommodate the rain cap 
assembly and to allow the center line of the plate to be placed 
approximately over the center of the stack outlet. When the stack stopper 
is being put in place on a stack having a rain cap, the plate will lift up 
the front edge of the rain cap, which overhangs the stack, and slide in 
underneath the cap to cover the stack outlet. 
Plate 63 also differs from plate 50 of FIG. 7 in having the two sides that 
pass through yoke 64 turned down, with attachment of the plate to the yoke 
by means of a wing nut 55 on a short bolt on each side of the plate 
instead of by an axle such as 54. Of course a plate such as 63, with or 
without the cutout, may be used on stacks without a rain cap, such as 
those shown in FIGS. 6 and 7. 
FIG. 9 also shows a different method of mounting the yoke on the support 
member. Yoke 64 is attached to tube 65, which has an inner diameter such 
that tube 65 can rotate about support member 22. As depicted the lower end 
of tube 65 rests on the offset of the support member. Above the upper end 
of the tube a removable bearing collar 66 is held on the support member by 
a locking pin 67, which passes through the collar and the support member. 
It is apparent that for a support member without an offset, a similar 
bearing collar fastened on the support member could be used to support the 
tube. FIG. 9 also shows another yoke 68 attached toward the lower end of 
tube 65 and conforming to the curvature of the stack. Yoke 68 serves to 
steady the whole assembly and assist in positioning the pad-bearing plate. 
Another feature of the embodiment of FIG. 9 is the capability of changing 
the plane of the offset support member relative to the plane of yoke 64. 
Two positions, right (R.) and left (L.) are shown for the support member, 
which can pivot about pivot axis P. Holes through tube 65 correspond to 
the left and right positions, and either set of holes can be aligned with 
a hole through the support member and held in the chosen position by means 
of locking pin 69. When the clearance between the tractor cab and the heat 
shield is not sufficient for proper positioning of yoke 23 and the 
associated tensioning assembly in one alignment of tube 65 and the support 
member, the alignment may be changed so that the clearance is no longer an 
impediment to use of the stack stopper. Alternative means for fixing the 
position of tube 65 relative to support member 22 will be apparent to 
those skilled in the art. 
It is apparent that the attachment of the yoke and plate assembly to tube 
65 in the manner shown permits the entire yoke, plate, and tube to be 
removed from the support member. It is also apparent that the pad-bearing 
plate assemblies of FIGS. 3, 6, and 7 could also be mounted on a removable 
tube such as 65, rather than being firmly fastened to a support member, so 
that they all could be used interchangeably on one support member or be 
placed on the stack by alternative means. 
One material suitable for use as the heat-resistant, resilient pad is 
silicone rubber sheet compounded to be heat resistant to 600.degree. F. 
Such materials are articles of commerce and are available from West 
American Rubber Company and Jedco, Inc. Pads fashioned from 1/4 inch sheet 
having durometer readings of 50 and 70 have been found to be useful, with 
the more resilient 50 durometer pad being preferred. It is expected that 
any material having similar heat-resistance and resiliency will be 
satisfactory. 
It is apparent that many variations from the particular embodiments 
exemplified above can be made without departing from the spirit of the 
present invention. In particular, various means for guiding, adjusting, 
and locking the position of the pad or for adjusting and locking the yoke 
relative to the heat shield or lower portion of the stack will be apparent 
to those skilled in the art. Similarly, other means of applying tension to 
the support member, such as springs or an arrangement of turnbuckles, are 
within the scope of the present invention, as are alternative means for 
varying the height of the plate and pad assembly relative to the heat 
shield yoke, e.g., at least a portion of the support member may be 
telescoping with means for locking in the desired position. Also, although 
the support member has been shown as being parallel to the exhaust stack 
and heat shield, whether offset or not, other configurations of the 
support member are possible, if perhaps not as convenient. While the 
embodiment shown in FIG. 1 has the position of the pad and plate assembly 
adjustable, in some applications this feature may not be required. For 
example, for a fleet of vehicles all having the same stack height, the pad 
and plate assembly could be in a fixed position with some saving in the 
cost of making the device.