Humboldt H-4156 Mechanical Loading Press for CBR - Manual (Page 4)

nnmm
Take readings of time versus travel at frequent enough intervals to control the rate of
penetration or flow within the required test limits.
Speed Selection:
Test Type
Speed in/min (mm/min)
California Bearing Ratio/Lime Bearing Ratio (CBRlLBR) 0.050 (1.27)
Unconfined Compression and UU Triaxial
or plastic material on 1.4" (38mm) diameter sample
0.028 (0 .71)
Unconfined Compression and UU Tri-axial for plastic
material on 2.8" (70mm) diameter sample
0.056 (1.42)
Soil - Cement 0.050 (1.27)
UU (Quick) Tri-axial for brittle material on
1.4" (38mm) diameter sample
0.008 (0.22)
UU (Quick) Tri-axial for brittle material on
2.8" (70mm) diameter sample
0.017 (0.43)
Marshall Stability and Flow 2.000 (50.8)
Direction of Travel:
The direction of the platen is up for clockwise crank rotation and down for
counterclockwise.
Load Ring, Penetration Piston & Strain Gauge:
The calibrated proving ring is attached directly to the cross-beam using the 3/4-16 x 7/8"
long bolt and attached to the bottom of the ring is the penetration piston. A dial
indicator holder is attached to the ring and a penetration dial is supplied attached
with a bracket to the piston and is adjustable on it.
Maximum Load:
The Machine is rated at 10,000lbf (44kN).
Accuracy Of Platen Speeds:
The speeds used in the various test are in fact the closing gap speed, i.e., the distance
between the cross-beam and the platen. These closing gap speeds will be dependent on
the stiffness of the sample being tested and the compressibility of any load measuring
device (such as the load ring). At high loads, some machine stretch may occur. The test
speeds used should therefore, take into account these factors.
Maintenance
Both the jack unit and the gearbox are packed with grease and do not normally
require further attention. The machine can generally be maintained by keeping it clean
and lightly oiling the exposed threads.