DETROIT DIESEL
Engine Equipment
HYDRAULIC STARTING SYSTEM (HYDROSTARTER)
ring gear and the control valve is opened, fluid under
The Hydrostarter System schematically illustrated in
pressure is forced out of the accumulator, by the
Fig. 6 is a complete hydraulic system for starting
expanding nitrogen gas, and flows into the starting
internal combustion engines. The system is automati-
motor which rapidly accelerates the engine to a high
cally recharged after each start, and can be manually
cranking speed. The used fluid returns directly to the
recharged. The starting potential remains during long
reservoir from the starter.
periods of inactivity, and continuous exposure to hot
or cold climates has no detrimental effect upon the
The engine-driven charging pump runs continuously
Hydrostarter system. Also, the Hydrostarter torque for
during engine operation and automatically recharges
a given pressure remains substantially the same
the accumulator. When the required pressure is
regardless of the ambient temperature.
attained in the accumulator, a valve within the pump
body opens and the fluid discharged by the pump is
The Hydrostarter system consists of a reservoir, an
by-passed to the reservoir. The system can be shut
engine-driven charging pump, a hand pump, a piston
down and the pressure in the accumulator will be
type accumulator, a starting motor and connecting
maintained.
hoses and fittings.
The precharge pressure of the accumulator is the
p r e s s u r e of the nitrogen gas with which the
accumulator is initially charged. This pressure must be
Operation
checked before the system pressure is raised for the
initial engine start. To check the precharge pressure,
Hydraulic fluid flows by gravity, or a slight vacuum,
open the relief valve, on the side of the hand pump,
from the reservoir to either the engine-driven pump or
approximately 1/2 turn, allowing the pressure gage to
the hand pump inlet. Fluid discharging from either
return to zero. Close the relief valve and pump several
p u m p outlet at high pressure flows into the
strokes on the hand pump. The gage should show a
accumulator and is stored at 3250 psi (22 383 kPa)
rapid pressure r i s e from zero to the nitrogen
under the pressure of compressed nitrogen gas.
precharge pressure, where it will remain without
change for several additional strokes of the pump.
When the starter is engaged with the engine flywheel
Fig. 6 - Schematic Diagram of Hydrostarter System Showing Oil Flow
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