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p 232
Chapter 3
Hydraulically-Driven Push Piers
CHAPTER 3
HYDRAULICALLY-DRIVEN PUSH PIERS
at similar flow rates, as shown in
Figure 3.8.2.a
.
Cylinders with less effective area will have faster
extension or retraction rates than cylinders
with more effective area. The effective area of
the cylinder in retraction mode is less than the
effective area in extension mode due to the
presence of the internal drive rod.
3.8.2.1 FSI Gasoline Powered
Hydraulic Pumps
FSGP5A is a single-stage gear pump driven
by a variable speed, 11 HP, 4-cycle gasoline
engine. Per manufacturer specifications, the
pump unit is capable of a 629 in
3
/min (2.7
gpm) flow rate at the maximum rated output
pressure of 4,000 psi and a speed of 3,600
rpm. FSGPZG6A is a dual-stage piston pump
driven by a variable speed, 13 HP, 4-cycle
gasoline engine. In the first stage of operation,
with an output pressure up to about 1,800
psi, the pump produces hydraulic flow of at
least 850 in
3
/min (3.7 gpm). The flow rate then
drops significantly through the second stage
of operation to 200 in
3
/min (0.87 gpm) at the
maximum rated output pressure of 10,000 psi
and a speed of 3,600 rpm. Pump performance
is affected by the output pressure and pump
speed. The output pressure may also be limited
by the pressure relief valve setting. The pump
output flow versus pressure curves for both
motors at a speed of 3,600 rpm are illustrated
in
Figure 3.8.2.1.a
.
Safety precautions must be followed when
using gasoline powered equipment. Ignition
sources must be kept away from the gasoline
tank and any gasoline vapor or fluid leakage
must be stopped. Exhaust fumes from
operation of gasoline engines require proper
ventilation, particularly when used indoors or
in confined spaces.
3.8.2.2 FSI Electric Powered
Hydraulic Pump Units
The FSEPZU4A hydraulic pump is driven by a
single speed, 1.125 HP, 110 volt electrical motor
capable of a 60 in
3
/min (0.26 gpm) flow rate at
the maximum rated output pressure of 10,000
psi. The FSEP554A hydraulic pump is driven by a
single speed, 1.125 HP, 110 volt electrical motor
capable of a 56 in
3
/min (0.24 gpm) flow rate at
the maximum rated output pressure of 10,000
psi. As can be seen by the pump performance
curves in
Figure 3.8.2.2.a
, the FSEPZU4A
and FSEP554A pump units have similar flow
performance above an output pressure of 1,500
psi. Again, pump performance is affected by the
output pressure and pump speed and the output
pressure may be limited by the pressure relief
valve setting.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
100
200
300
400
500
600
700
800
900
1000
0
2000
4000
6000
8000 10000
Flow (gpm)
Flow (in
3
/min)
Pressure (psi)
FSGPZG6A (3600 rpm)
FSGP5A (3600 rpm)
Figure 3.8.2.1.a
FSI gasoline
powered hydraulic pump curves
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
100
200
300
400
500
600
700
800
0 2000 4000 6000 8000 10000
Flow (gpm)
Flow (in
3
/min)
Pressure (psi)
FSEPZU4A
FSEP554A
Figure 3.8.2.2.a
FSI Electric
Powered Hydraulic Pump Curves