TM 5-3820-233-12/2
Roll Crusher is running partially empty, it is advisable to
CAUTION
in- crease the Primary Jaw Crusher opening to allow the
Do not stop the Secondary Unit while the
Secondary Roll Crusher to do more crushing here again
Primary Unit is passing the material into the
never feed the Roll Crusher material that exceeds the
Feed Conveyor Hopper of the Secondary
maximum size feed or "flooding" of the unit will result.
Unit, except in cases of emergency.
The Roll Crusher is considered "flooded" when material
consistently builds up in the hopper. It is intended to
Another reason for stopping feed to the Secondary Unit
provide surge capacity for occasional overloads only.
is when there are no trucks or trailers available to haul
the finished product from the Plant. The Secondary Unit
2-4. Secondary Unit Product Sizes
has a limited storage area under the Screen and it will be
Even though the Roll Crusher is automatically fed by
necessary to stop the feed to the Secondary Unit if
receiving oversize material from the top deck of the
finished product dump trucks or carriers are not available
vibrating screen, the operator must regularly observe the
at all times to carry material from the delivery conveyors.
material entering the Roll Crusher hopper to be certain
Continued operation of the Primary and Secondary Units
the crusher is being fed enough material to be working to
until hoppers are filled beyond capacity and material is
capacity, and yet not being flooded.
lodged between the moving screen box and hopper will
cause breakage of the secondary screen box and
gives average material sizes that can be expected. This
frames. The capacity of the Secondary Crushing and
can not be taken as a guarantee of just what size you will
Screening Unit will vary greatly according to type and
get at all times, because conditions change. The
size of material being reduced in the Roll Crusher and
following example explains chart use:
the Primary Unit operator to maintain a balance between
Example: To find the percentage of each size of the
the discharge openings in the primary unit and roll
product in the roll crusher, set a 1".Find 1" at the top of
crusher in the secondary unit to operate at maximum
the chart, follow the vertical column down until it
efficiency and capacity. The speed of the roll crusher is
intersects with the horizontal range size column. The
determined in feet per minute of the outside diameter of
first figure is 2" and 2%-c, indicating that 2% of the
roll shells. Under normal conditions, the shells are
material will be over 2" and 98"% passing. The figures
rotating at approximately 500 feet per minute. The exact
between the heavy lines indicate the amount of oversize
RPM of the countershaft flywheel is predetermined and
that can be expected at a given setting. By following
normally stenciled on the crusher, which will give the
down the vertical column you will find the following:
correct shell speed per size of roll and type of material
Over 1" ...........................................................
27
being crushed.(table 2-1.) If the Roll Crusher opening
1"-7/8" ............................................................
7%
between the roll shells is set to crush the finished size
7/8"-3/4" .........................................................
%
3/4"-5/8" .........................................................
5-1/2%
is necessary for the Primary Unit operator to continually
5/8"-1/2" .........................................................
8%
stop the feed from the Reciprocating Feeder to the Jaw
1/2"-3/8" ......................................................... 10-1/2%
Crusher to allow the Secondary Unit to catch up to the
3/8"-5/ 16" ......................................................
3%
Primary, it will be necessary to reduce the opening of the
5/16"-1/4" .......................................................
5%
Jaw Crusher to allow it to do more crushing and
1/4"-4M...........................................................
5-1/2%
consequently reduce the crushing load on the Roll
4M-8M ............................................................
7.6%
Crusher. However, do not reduce the Jaw Crusher
8M-10M ..........................................................
1.6%
setting below the minimum recommendation opening at
10M Minus......................................................
83%
any time. If it is not possible to close the Jaw Crusher it
TOTAL
100%o
is avisable to reduce the stroke of the reciprocating
Feeder so that a more continuous operation of both units
is possible. How- ever, if the opposite is true and the
Section II. MOVEMENT TOA NEW WORKSITE
2-5. Dismantling for Movement
2-6. Folding Side Conveyors
For normal road travel or shipment by rail none of the
major components need be removed.
The side
follows:
a. Remove bolts in tail break to allow conveyor to be
conveyors are folded flat to the sides of the unit. When
movement by air or foreign rail travel is required, the
lowered.
b. Remove the rock conveyor drive guards and the
engine, feed conveyor, elevating wheel side conveyors
and walkway must be re- moved for weight and height
V-belts on the roll crusher drive to provide clearance
reduction.
when folding sand delivery conveyor.
2-6