Rexnord 1874, Engineering Manual

Page: 19 / 53

TYPICAL CONVEYOR CONSTRUCTION
VIEW A
-
A
GUIDE CLEARANCE
CHAIN WIDTH
+ "A"
Figure 9 - Typical Conveyor Construction
A
A
Calculation of guide clearance "GC" for
MatTop
®
Conveyors
For conveyors operating at room temperature
(70°F to 21°C);
GC = actual chain width + A (see Table 4 for A)
For conveyors operating at elevated
temperatures one must take thermal
expansion of the chain into account.
The actual width will increase by an
amount that is dependent upon
temperature, chain width, and the
coefficient of thermal expansion of
the plastic.
The coefficient of thermal expansion is:
C
Thermal =
0.001 in
(
0.15 mm
)
Expansion
or
m · °C
Ft · °F
Dimension "A" Conveyor Length
3/8
5/8
3/4
Up to 30'
30' - 50'
Over 50'
TABLE 4 STANDARD CONVEYOR
GUIDE CLEARANCE
Calculation of "GC" at Elevated Temperatures
Assume a 12ft. wide, 45 ft. lone pasteurizer
operating at an average temperature of 190°F.
1. The increase in the width ( W) due to the
temperature of 190° can be found as shown:
W = W (chain width in Ft or m)
x C
Thermal Expansion
x T (Temp. diff. from room
temp. of 70°F, 21°C)
W = [12 ft.] x
[
0.001 in
]
x [190°F - 70°F]
Ft · °F
W = 1.44 in.
2. Allow for the standard clearance, "A",
based upon conveyor length. The conveyor
in the example is 45 ft. long. Table 4 gives
"A" = 5/8 in for conveyors between 30 ft. and 50 ft.
3. The total "GC" for this example is:
GC =12ft. (chain width@ 70°F)
+1.44 in. (expansion due to temperature)
+ 5/8 in. (standard clearance)
GC = 144 in. + 1.44 in. + 0.625 in.
GC = 146.065 146 1/16 in.
~
~
1.
2.
SELECTION
PROCEDURE
cont.
Conveyor
Design and
Construction
Re
x
®
MatT
op
®
Chains
Rex ® Engineering Manual MT-6