42.44
horsepower
hp (metric)
1.014
Appendix-225
FM 5-499
Table A-1. Metric conversion chart
To Convert
Into
Multiply By
Centimeters
2.540
Inches
Meters
2.540 x 10-2
Millimeters
25.40
Centimeters
1.6093 x 105
Miles (statute)
Meters
1,609.3
Kilometers
1.609.3
cms/sec
44.70
Miles/hr
kms/hr
1.609
kms/min
0.02682
Pounds
Kilograms
0.4536
Pounds/sq in (psi)
kgs/sq meter
703.1
Square Inches
sq centimeters
6.452
sq cms
929.0
Square feet
sq meters
0.09290
sq millimeters
9.290 x 104
sq kms
2.590
Square miles
sq meters
2.590 x 106
Kilograms
907.1848
Tons
Tons (metric)
.9078
Centimeters
91.44
Kilometers
9.144 x 10-4
Yards
Meters
0.9144
Millimeters
914.4
Temperature Conversion Chart:
Celsius = 5/9 (°F - 32)
Fahrenheit = 9/5 (°C + 32)
Appendix-226
FM 5-499
Glossary
°F
degree Fahrehheit
AC
alternating current
ASA
American Standards Association
ATTN
attention
axial piston pump
A pump in which the pistons stroke in the same direc-
tion on the cylinder block's centerline; these pumps
are either an in-line or angle design.
Bernoulli's Principle
Law which states that the static pressure of a moving
liquid varies inversely with its velocity; that is, as ve-
locity increases, static pressure decreases.
BTU
British thermal unit
capacity
Same as volumetric output.
cavitation
A condition that occurs in pumping when available
fluid does not fill the existing space; cavitation causes
erosion of the metal in the inlet and speeds deteriora-
tion of the hydraulic oil.
centrifugal pump
A nonpositive-displacement pump that is used in a
hydraulic system where a large volume of flow is re-
quired at relatively low pressures; a centrifugal pump
is either a volute or diffuser type.
cfs
cubic foot (feet) per second
chassis ground
The difference of potential between a point in the cir-
cuit and a ground point that is measured by the volt-
meter. Also called common ground. See also earth
ground; ground; zero reference point.
Glossary-227
FM 5-499
closed-center system
A pump system where the pump continues to operate
against a load in the neutral condition.
common ground
Same as chassis ground.
cyl
cylinder
cylinder
A hydraulic actuator that is constructed of a piston or
plunger which operates in a cylindrical housing by the
action of liquid under pressure; a cylinder can be one
of several types: single acting, double acting, differen-
tial, nondifferential, ram type, piston type, cushioned,
or lockout.
DA
Department of the Army
DC
direct current
delivery rate
Same as volumetric output.
directional-control valves
Valves that control the flow direction; they can be a
poppet, a sliding-spool, a check, a two-way, or a four-
way valve. See also flow-control valves, pressure-
control valves; valves.
displacement
The amount of liquid that is transferred from the
pump's inlet to its outlet in one revolution or cycle;
displacement is either fixed or variable. See also
fixed-displacement pump; variable-displacement
pump.
displacement principle
Principle which explains how fluid is taken in at one
point and is displaced to another point; displacement
is either nonpositive or positive. See also nonpositive-
displacement pump; positive-displacement pump.
earth ground
Connections to ground that are made for safety rea-
sons. See also chassis ground; ground; zero refer-
ence point.
energy
The ability to do work, expressed in ft lb. See also
friction; heat energy; kinetic energy; potential
energy.
fixed-displacement pump
A pump in which the GPM output can be changed only
by varying the drive speed. See also displacement;
variable-displacement pump.
flow
The movement of the hydraulic fluid caused by a dif-
ference in the pressure at two points; velocity and
flow rate are the two ways to measure flow. See also
Glossary-228
FM 5-499
flow rate; velocity.
flow rate
The measure of how much volume of a liquid passes a
gpoint in a given time, measure in GPM. See also
flow; velocity.
flow-control valves
Valves that are used to control the actuator speed by
metering the flow; they can be a gate, a globe, a nee-
dle, a restrictor, an orifice-check, or a flow-equlizer
valve. See also directional-control valves;
pressure-control valves; valves.
FM
field manual
force
Anything that tends to produce or modify motion, ex-
pressed in pounds.
fps
foot (feet) per second
FPT
flow, pressure, and temperature
friction
The resistance to relative motion between two bodies.
See also energy; heat energy; kinetic energy; po-
tential energy.
ft
foot (feet)
ft lb
foot-pound
GPM
gallon(s) per minute
ground
A point of reference in an electrical circuit to which all
circuit voltages are compared; circuit voltages are ei-
ther positive or negative with respect to ground. See
also chassis ground; earth ground; zero refer-
ence point.
head
The vertical distance between two levels in a fluid.
heat energy
The energy a body possesses because of its heat; con-
sidered a dynamic factor. See also energy; friction
kinetic energy; potential energy.
hp
horsepower; standard unit of power; one HP is equal
to 550 ft lb of work every second.
HP
hydraulic hp
HQ
headquarters
hydraulic actuator
A piece of equipment that receives pressure energy
Glossary-229
FM 5-499
and converts it to mechnical force and motion.
hydraulic motors
A piece of equipment that converts hydraulic energy
into mechanical energy; hydraulic motors can be gear,
vane, or piston types.
hydraulic testers
lightweight units used to check or troubleshoot a hy-
draulic-powered system.
hydraulics
The science of transmitting force and/or motion
through the medium of a confined liquid.
ID
inside diameter
JIC
Joint Industry Conference
kinetic energy
The energy a body possesses because of its motion; the
amount of kinetic energy in a moving liquid is directly
proportional to the square of its velocity; considered a
dynamic factor. See also friction; heat energy; po-
tential energy; velocity pressure.
laminar flow
Flow that occurs when particles of a liquid move in
straight lines parallel to the flow direction. See also
turbulent flow.
lb
pound
MO
Missouri
N C
normally closed
N O
normally open
nonpositive-displacement pump
This type of pump discharges liquid in a continuous
flow. See also displacement principle; positive-
displacement pump.
OD
outside diameter
open-center system
A pump system where the pump's output has a free
flow path back to the reservoir in the circuit's neutral
condition.
Pascal's Law
Basic law of hydraulics that Blaise Pascal formulated
in the 17th century; Pascal states that pressure in a
Glossary-230
FM 5-499
confined fluid is transmitted undiminished in every
direction and acts with equal force on equal area and
at right angles to the container's walls.
positive-displacement pump
This type of pump discharges volumes of liquid that
are separated by periods of no discharge. See also dis-
placement principle; nonpositive-displacement
pump.
potential energy
Energy due to position; in hydraulics, potential ener-
gy is a static factor. See also energy; friction; heat
energy; kinetic energy.
pressure
The force exerted against a specific area, expressed in
psi.
pressure-control valves
Valves that may limit or regulate pressure, create a
particular pressure condition required for control, or
cause actuators to operate in a specific order. Pres-
sure-control valves can be a relief, a pressure-reduc-
ing, a sequence, or a counterbalance valve. See also
directional-control valves; flow-control valves;
valves.
psi
pound(s) per square inch
radial piston pump
A pump in which the pistons are arranged like wheel
spokes in a short cylindrical block.
reciprocating pump
A type of pump that depends on a reciprocating mo-
tion to transmit liquid from its inlet side to its outlet
side.
resistance
A condition in a hydraulic system that is usually
caused by a restriction or obstruction in the path or
flow.
rotary pump
A positive-displacement pump in which rotary motion
carries the liquid from the pump's inlet to its oulet.
rpm
revolution(s) per minute
slippage
The measure of a pump's efficiency expressed in per-
cent; oil leaks from the pressure outlet to a low-pres-
sure area or back to the inlet; some slippage is
designed into pump systems for lubrication purposes.
SPDT
single pole-double throw switch
SPST
single pole-single throw switch
sq in
square inches
Glossary-231
FM 5-499
STOP system
Troubleshooting system in hydraulics in which a per-
son should Study the cirucit diagrams, Test by using
a reliable tester, Organize the knowledge gained from
the circuit-test results, and Perform repairs, taking
time to do the job well.
torque
Circular force on an object.
turbulent flow
Flow that develops when flow speed increases beyond
a given point. See also laminar flow.
two-stage pump
A pump that consists of two separate pump assem-
blies that are contained in one housing.
typical mobile circuits
Hydraulic-lift, power-steering, and road-patrol-truck
circuits.
USAES
United States Army Engineer School
USASI
United States of American Standards Institute
valves
Objects in a hydraulic system that control the opera-
tion of the actuators; valves regulate pressure by cre-
ating special pressure conditions and by controlling
how much oil will flow in portions of the circuit and
where it will go. See also directional-control
valves; flow-control valves; pressure-control
valves.
vane-type pump
A pump in which a slotted rotor splined to a drive
shaft rotates between closely fitted side plates that
are inside of an elliptical- or circular-shaped ring;
vane pumps can be couble, unbalanced, or balanced.
variable-displacement pump
A pump in which the pumping-chamber sizes can be
changed; the GPM delivery can be changed by moving
the displacement control, changing the drive speed, or
doing both. See also displacement; fixed-
displacement pump.
velocity
The average speed of a fluid's particles past a given
point, measured in fps. See also flow; flow rate.
velocity pressure
Pressure caused by kinetic energy. See also kinetic
energy.
volumetric output
The amount of liquid a pump can deliver at its outlet
port per unit of time at a given drive speed, usually
expressed in GPM or cubic inches per minute. Also
called delivery rate or capacity.
Glossary-232
FM 5-499
V
volt
VOM
volt-ohm-millammeter
work
The measure of force multiplied by distance.
zero reference point
voltage point in an electrical circuit that is neither
negative or positive. See also chassis ground, earth
ground; ground.
Glossary-233
FM 5-499
References
SOURCES USED
These are the sources quoted or paraphrased in this publication.
Nonmilitary Publications
Hydraulics. Deere and Company Service Publications, Moline, Illinois. 1997.
Industrial Hyydraulics Manual. Vickers Training Center, Rochester Hills, Michigan. 1993.
DOCUMENTS NEEDED
These documents must be available to the users of this publication;
Department of the Army Forms
DA Form 2028. Recommended Changes to Publications and Blank Forms. February 1974.
References-1
Index
A
accumulators (para 2-6)
bag-type (para 2-6b)
maintenance of (para 2-6d)
piston-type (para 2-6c)
spring-loaded (para2-6a)
actuator
air vents (para 4-3j)
American Standards Association (ASA) (para 6-2)
area (para 1-1b)
ASA. See American Standards Association (ASA)
assembling a clamp-type coupling (para 2-10d)
assembling a conductor (para 2-10d)
B
baffle plate (para 2-3f)
bends in tubing (para 2-9d)
Bernouilli’s principle (para 1-4d)
C
camshaft (para 5-2d(1))
capacity (para 3-2)
centrifugal force (para 4-4b)
cfs. See cubic foot (feet) per second (cfs)
circuits
hydraulic-lift (para 6-3a)
mobile (para 6-3a)
operation problems in (para 6-4a)
power-steering (para 6-3b)
road-patrol-truck (para 6-3c)
testing (para 6-4b)
troubleshooting (para 6-4)
circulatory system (para 2-9)
requirements (para 2-9)
colors in figures (para 2-2)
connecting tubing (para 2-9d)
connectors (para 2-10)
flared (para 2-10b)
threaded (para 2-10a)
couplings (para 2-3f)
flexible-hose (para 2-10c)
cubic foot (feet) per second (cfs) (para 2-7)
cylinder block (para 3-8a(2)), (para 3-8a(5))
cylinder housing (para 4-1)
cylinder ports (para 4-2)
cylinders (para 4-1)
construction of (para 4-2)
cushioned (para 4-1g)
differential (para 4-1c)
double-acting (4-1b)
lockout (para 4-1h)
nondifferential (para 4-1d)
piston (para 4-1)
piston-type (para 4-1f)
problems with, abrasives on a piston rod (para 4-3h)
problems with, burrs on a piston rod (para 4-3i)
problems with, creeping (para 4-3c)
problems with, loose mounting (para 4-3e)
problems with, misalignment (para 4-3f)
problems with, no lubrication (para 4-3g)
problems with, sluggish operation (para 4-3d)
ram-type (para 4-1), (para 4-1e)
single-acting (para 4-1a)
D
dash number of tubing (para 2-9a)
delivery rate (para 3-2)
diagrams
hydraulic-circuit (para 6-1)
hydraulic-circuit, block (para 6-1a)
hydraulic-circuit, cutaway (para 6-1b)
diode (para 7-2b(5))
displacement (para 3-3), (para 4-4), (para 4-4c(1))
distance (para 1-2)
drive shaft (para 3-8b(1))
E
electrical equipment (para 7-4a)
practices (para 7-4b)
safety (para 7-4)
energy (para 1-4)
heat (para 1-4c)
kinetic (para 1-4b), (para 1-4d)
potential (para 1-4a), (para 1-4d
F
filters (para 2-4b)
active, absorbent (para 2-5)
element, depth-type (para 2-5)
element, edge-type (para 2-5)
element, surface-type (para 2-5)
full-flow (para 2-4b(1))
inactive, absorbent (para 2-5)
mechanical (para 2-5)
proportional-flow (para 2-4b(2))
fittings (para 2-10)
crosses (para 2-10b)
elbows (para 2-10b)
skived (para 2-10d)
unions (para 2-10b)
flared connectors leaking (para 2-10b)
flaring a tube (para 2-9d)
flow (para 1-3), (para 2-7), (para 3-1), (para 5-2c(2)), (para 5-2e)
laminar (para 1-4c)
turbulent (para 1-4c)
flow, pressure, and temperature (FPT) (para 6-4d)
fluid pressure (para 4-1f)
foot (feet) per second (fps) (para 1-3a)
foot-pound (ft lb) (para 1-4)
force (para 1-1b), (para 1-2)
fps. See foot (feet) per second (fps)
FPT. See flow, pressure, and temperature (FPT)
friction (para 1-4c), (para 1-4d)
ft lb. See foot-pound (ft lb)
G
gallon(s) per minute (GPM) (para 1-3b)
gas (para 1-1)
gauges
pressure (para 2-7)
GPM. See gallon(s) per minute (GPM)
gravity (para 4-1f)
ground (para 7-3)
chassis or common (para 7-3b)
earth (para 7-3a)
zero reference point (para 7-3c)
H
head (para 1-1a), (para 1-4c)
horsepower (HP) (para 1-4f), (para 2-1c(3))
hose (para 2-9c(1))
rubber (para 2-9c(1))
Teflon-type (para 2-9c(2))
HP. See horsepower (HP)
hydraulic balance (para 5-1)
hydraulic boost (para 6-3b)
hydraulic motors (para 4-4)
bent-axis piston-type (para 4-4c(2))
gear-type (para 4-4a)
i