During the plant erection stage, plans should be
made for the layout of roads. Well-planned roads are
needed to prevent congestion, decrease the time haul
units are in the plant, and for safety. Road networks are
needed for the following:
1. Haul units bringing rock from the quarry
2. Trucks hauling the product aggregate to
3. Service vehicles, such as crew, fuel, and
If possible, plant roads should be one way and be
wide enough for the largest haul unit expected. They
should be designed to support heavy loads.
Plant roads must be maintained constantly. In dry
areas where there is little rainfall, a water truck is
required to wet down the roads to control the dust. In
wet areas crushed rock should be used on the roads to
keep haul units from sliding off into ditches. A
maximum speed limit should be posted for vehicular
traffic within the crusher area and on the haul roads.
The importance of proper site preparation and
proper stationing of the plant cannot be
overemphasized. Your site for stationing the plant
should be flat, level, and well compacted. Crushing and
screening plants may be operated for short periods of
time from the wheelbase. But it is advantageous on
longer and more deliberate jobs, from a maintenance
standpoint, not to operate the plant until it has been
blocked and leveled with the tires clear of the ground.
You should include the following steps in the
operational start-up phase:
Operating instructions. All appropriate technical
manuals must be reviewed and studied before the
beginning of plant operations.
Training. You should train all personnel assigned
to operate and maintain the plant. During this training
period the importance of site preparation, setup,
maintenance, and safety should be emphasized. You
should keep the proper tools, materials, and manuals at
the site. A high rate of aggregate production should not
be expected until personnel become familiar with the
Tools. The tools used in maintenance and assembl y
of the plant are included in the mechanics tool kit which
is part of the NCF TOA. Basic issue items that are
incorporated with each plant are also available.
Leveling. The plant should be leveled before initial
operation and should be frequently checked while in
operation. Leveling should be done on the frame for
longitudinal leveling. A rigid, straight plank should be
used across the unit frame rails for transverse leveling.
The leveling should be checked at several points
throughout the unit.
Blocking. Blocks should be installed under each
side of the tandem axles and under the dolly axle or the
fifth wheel plate to raise the tires or landing gear clear
of the ground. Place blocking or cribbing parallel to the
longitudinal center line of the unit.
Hydraulic jacks. Jacks should be on each side of
the unit opposite each other and under the unit frame
members. Raise and lower the jacks in equal increments
to prevent bending of the frame.
Screw type of stabilizing jacks. Tighten the screw
type of stabilizing jacks to maximum torque after the
crusher has been blocked and leveled.
retorquing should be continued throughout the
Nuts and bolts. Ensure all bolts are tight by
torquing the nuts, not the bolt heads. Additionally,
operation of the plant. This should be performed at
critical locations and during the initial operation to
assure proper seating and prevent parts from loosening
and getting out of adjustment. Any adjustments
required, such as movement of trunnion wheels on the
trunnion shaft, should be made during the first hours of
Jaw plates and roll shells are held in place by
wedges which are secured by keeper bolts. The wedges
must be driven home with a sledge hammer while
constantly applying torque with the wrench to achieve
Visual inspection. To prevent damage and eventual
breakage, you should visually inspect the plant
constantly to detect any misadjustment or loss of
adjustment. Visual inspections should be made from
ground level, from the platform, and from walkways.
All adjustments should be checked with the components
operating while empty and rechecked while loaded with
The 75-ton-per-hour plant is used in any of four
basic setups, depending upon the raw material available