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TM 10-3930-671-24
General
A.
PURPOSE OF THE MANUAL
This manual is expressly intended to provide sufficient
information for qualified technicians experienced in
diesel engines and diesel injection equipment, to
disassemble and reassemble the Roosa Master DB2-
type fuel injection pump and to make such adjustments
and parts replacements as may be needed. It is
recommended that an inexperienced person refrain from
making adjustments and repairs, as such action may
result in very extensive damage to the pump and
possibly to the engine.
No service should be performed on the pump before
making a careful study of this manual and becoming
familiar with the principles and instructions which follow.
Since several critical adjustments of the injection pump
are required which cannot readily be made on the
engine, it is necessary that the service be performed in a
facility equipped with the proper special tools and an
approved, motorized test stand.
This
manual
completely
describes
the
operating
principles of the pump and most accessories. Only
through a thorough knowledge of these principles can
the serviceman locate and correct possible operational
defects.
B.
MODEL NUMBER SYSTEM
It is necessary to understand the model number system
for reference to the proper sections of this manual
covering operation and maintenance of the pump.
EXAMPLE:
a
b
c
d
e
Model Number DB2
6
33
JN
3000
a.
DB2-D Series Pump, 13-Rotor, 2nd generation
b.
6- Number of cylinders. (Available in 2, 3, 4, 6
and 8 cylinder configurations.)
c.
33- Abbreviation of plunger diameter.
25-.250"(6.35mm) 31- .310’"(7.87mm)
27- .270"(6.86mm) 33- .330"(8.38mm)
29- .290"(7.37mm) 35- .350"(8.89mm)
d.
JN -Accessory code (See S.B. No. 63)
The code pertains to combinations of special
accessories such as electrical shutoff, automatic
advance, variable speed droop adjustment, etc.
See the proper service bulletin or manual section
for
operation
and
construction
of
these
accessories.
Include this in any reference to the pump.
e.
3000 - Specification Number
Determines selection of parts and adjustments
for a given application. Must be included in any
reference to the pump.
NOTE
Pump rotation and method of mounting are provided
under special notes on individual pump specifications.
C.
GENERAL INFORMATION
In a diesel engine, air is drawn into the cylinder through
the intake valve and compressed. A metered quantity of
fuel is then injected into the cylinder, producing a
combustible mixture. This mixture ignites from heat of
compression, and the expanding gases force the piston
downward.
The function of a diesel fuel injection pump is to
accurately meter and deliver fuel to a nozzle in each
cylinder and to inject it at high pressure into the
combustion chamber at precisely timed intervals. The
extreme precision necessary can well be appreciated
since this cycle must be repeated thousands of times per
minute with virtually no variation in timing or amount of
fuel injected. The injection pump is truly the heart of the
diesel engine.
ROOSA MASTER
MODEL DB2 DIESEL INJECTION PUMP
The model DB2 injection pump is described as an
opposed-plunger, inlet-metered, positive-displacement,
distributor-type pump. The DB2 pump incorporates a
single
pumping
chamber.
Simplicity,
the
prime
advantage of Roosa Master design, contributes to lower
initial cost, greater reliability, ease of service and lower
maintenance cost.
The necessity for cost reduction is more apparent in the
small diesel engine where the injection equipment
represents a greater percentage of the cost. Since the
basic model has but 100 odd parts, and only four main
rotating members, there is less chance of failure.
Repairs are generally inexpensive. Today’s small, high-
output engines have created a need for improved, yet
low cost, injection equipment capable of higher speed
operation, quieter running and lower exhaust emissions.
F-212
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