TM 5-3820-233-12/1
(5) Inspect V-belts and conveyor belts for proper
important that explosive pattern be designed to obtain
tension.
maximum breakage. All material crushed or reduced to a
(6) Remove wood block from between jaws in jaw
crushable size in the quarry will increase the capacity of
crusher chamber.
the plant and reduce maganese jaw and roll shell wear.
Generally the Primary Plant is used with the Secondary
Crushing and Screening Plant to obtain a finished size
NOTE
For operation of the secondary unit (crusher
produce or two products. It is important that the operator
screening unit) refer to TM 5-3820-233-
on the primary make sure that the secondary plant is
12/2.
operating satisfactorily and all components are at full
recommended speed before starting to crush material on
2-3. Jaw Crusher Product Sizes
the jaw crusher. It is necessary to always stop the feed to
the primary jaw crusher before shutting the secondary
The jaw crusher percentage table 2-1, gives average
crushing and screening plant down unless for
material sizes that can be expected. This cannot be
emergency. The size of feed from the primary jaw
taken as a guarantee of just what size materials you will
crusher to the secondary roll crusher must be no larger
get at all times because conditions change. The following
than the maximum size of material recommended to
example explains the charts used.
feed the roll crusher. (See roll crusher feed size chart,
Example. To find the percentage of each size in the
TM 5-3820-233-12/2, for this information). The operator
product of a crusher, adjust it to 1-1/2" close setting, find 1-
must be aware of the availability of the finished hauling
1/2" at the top of the chart, follow the vertical column down
equipment such as dump trucks and trailers. The
until it intercepts with the horizontal range size column. The
secondary plant has a limited storage area under the
first reading is 2-3/4" and 4% indicating that 4% of the material
screen and it will be necessary to stop the feed to the
will be over 2-3/4" and 96% passing. By following down the
secondary if finished product dump trucks or carriers are
vertical column you can find the following:
not available at all times to carry the material from the
Over 1 1/2" ................................................................ 29%
product conveyors. Continued operation of the primary
1 1/2" - 1 1/4.............................................................. 8 1/2%
and secondary plant until hoppers are filled beyond
1 1/4" - 1" .................................................................. 10 1/2%
capacity and material is lodged between the moving
1" - 7/8" ..................................................................... 5 1/2%
7/8" - 3/4" .................................................................. 7 1/2%
screen box and hopper will cause breakage of the
3/4 - 5/8" ................................................................... 3.8%
screen box and frames. The capacity of the secondary
5/8 - 1/2" ................................................................... 5.4%
crushing and screening plant will vary greatly according
1/2" - 3/8" .................................................................. 7.3%
to type and size of material being reduce in the roll
3/8" - 5/16" ................................................................ 2 1/2%
5/16" - 1/4" ................................................................ 3%
crusher and it is the duty of the primary plant operator to
1/4" - 4M.................................................................... 4.2%
control the reciprocating feeder and send only enough
4M - 8M..................................................................... 5.5%
material thru the jaw crusher to keep the secondary
8M minus .................................................................. 1.1%
crushing and screening plant working at full capacity.
Total100%
Failure to heed warning of the secondary plant being
over-loaded will usually cause stoppage of the secondary
The figures between the heavy lines indicate the amount
plant and entail considerable hand labor to clean the
of oversize that can be expected at a given setting.
overflow of material in this plant.
2-4. Equipment Conversion
CAUTION
In extremely cold temperatures use
The primary plant can be used in gravel or rock and will
possibly be required to crush various types and sizes of
caution when feeding the portable
raw material must be smaller in two dimensions than in
jaw crusher plan materials such as
the opening of the top of the jaw crusher. Feeding
frozen aggregate, frozen clay or silt
oversize material that will not go into the crusher will
which will cause compaction and
entail considerable sledging and hand labor and
result in toggle breakage. Feed plant
consequently greatly reduce hourly capacity. When using
at a reduced rate and observe for
dynamite or other explosives in the quarry or gravel pit to
normal operation.
loosen and produce the size of raw material, it is
2-3
