Lesson 1/Learning Event 2
LEARNING EVENT 2:
IDENTIFY THE MODELS
AND COMPONENTS OF THE 50-GPM PUMP
Several models of the 50-GPM Pump exist. The models vary according to the manufacturer of
the engine and the pump.
The pump can be equipped with two different electric motors or three different types of military
standard gasoline engine. Except for a brief description of the electric motors and alternate
gasoline engines, this subcourse will deal with the Barnes Model 17570 pump with a typical
military standard gasoline engine.
Electric Motors
A Doerr model 62530HW electric motor is provided with Barnes model 22270 and Carver model
KEM155S pumps. The Barnes model US4CCE pump is equipped with a Baldor Electric
Company Model 617M electric motor. Baldor motors and Doerr motors are interchangeable as
complete motors. Individual components of Baldor motors are not interchangeable with Doerr
motors, nor are Doerr parts interchangeable with Baldor motors.
The electric motors are two-horsepower units encased in heavy-duty drip-proof housings. They
are air cooled and are provided with permanently lubricated bearings. This subcourse will deal
mainly with the gasoline engine models since operation and maintenance of the electric motors
are relatively simple. The pump units on the electric and gasoline models are the same.
Gasoline Engines
The military standard engines described in this subcourse are the 4-stroke cycle. overhead-valve,
air-cooled type. These engines have design features for radio frequency interference suppression,
complete with fungus proofing. The 1 1/2 HP Military Standard Engine, Model 1A08-3, is
illustrated in figure 2 on page 6. It and other engines develop 1 1/2 HP at 3,600 revolutions per
minute (R.P.M.). These engines are designed with a splash lubrication system, wet and dry air
cleaners, 18-millimeter spark plugs, centrifugal-type mechanical governors, diaphragm fuel
pumps, and capabilities of efficient starting and operation at temperatures to minus 25 F. (-31.7
C.).
Controls and Instruments
The 50-GPM Pump (figure 1 on page 2) consists of the motor and the pump unit mounted on the
frame. The controls are relatively simple, consisting of an ignition switch (on the MS 1A08-3
model only) or a stop button (on the MS 1A08-1 model), a choke control, and a fuel valve. A
plug in the top of the pump body and a draincock at the bottom of the pump are used to prime the
pump and
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