To convert from
Temperature
Metric Conversion Factors
To
Use this formula
temperature Celsius, tC
temperature Fahrenheit, tF
tF = 1.8tC + 32
temperature Fahrenheit, tF
temperature Celsius, tC
tC = (tF - 32)/1.8
temperature Celsius, tC
temperature Kelvin, tK
tK = tC + 273.15
temperature Fahrenheit, tF
temperature Kelvin, tK
tK = (tF + 459.67)/1.8
temperature Kelvin, tK
temperature Celsius, tC
tC = tK - 273.15
temperature Kelvin, tK
temperature Fahrenheit, tF
tF = 1.8tK - 459.67
temperature Kelvin, tK
temperature Rankine, tR
tR = 9/5tK
temperature Rankine, tR
temperature Kelvin, tK
tK = 5/9tR
Multiply
millimetre
millimetre
centimetre
centimetre
metre
metre
metre
metre
inch
inch
inch
foot
foot
foot
yard
mile (US statute)
mile (US statute)
Multiply
Length
By
0.003280840
0.0397008
0.03280840
0.3937008
39.37008
3.280840
1.093613
0.0006213712
0.0254*
2.54*
25.4*
0.3048*
30.48*
304.8*
0.9144*
1,609.344*
1.609344*
Mass
By
Volume
Multiply
centimetre3
gallon
gallon
gallon
gallon
inch3
inch3
inch3
(UK
(UK
(US
(US
liquid)
liquid)
liquid)
liquid)
litre
litre
litre
metre3
metre3
metre3
metre3
foot
inch
foot
inch
inch
foot
yard
mile (US statute)
16,387.06
16.38706
0.00001638706
millimetre3 (mm3)
centimetre3 (cm3)
metre3 (m3)
metre3 (m3)
gallon (UK liquid)
gallon (US liquid)
0.001*
0.2199692
0.2641720
219.9692
264.1720
35.31466
1000.*
gallon (UK liquid)
gallon (US liquid)
foot3
litre
metre (m)
centimetre (cm)
millimetre (mm)
metre (m)
centimetre (cm)
millimetre (mm)
metre (m)
metre (m)
kilometre (km)
To obtain
Webtec Products Limited
For a comprehensive source of technical
information as well as the full range of Webster
hydraulic test equipment and Webtec hydraulic
components, please visit our web site at:
Multiply
gallon (US liquid)/minute
gallon (US liquid)/minute
gallon (US liquid)/minute
pound
0.4535924
kilogram (kg)
litre/minute
litre/minute
litre/minute
1,016.047
907.1847
1,000.*
metre3 (m3)
litre
metre3 (m3)
litre
inch3
gram (g)
kilogram (kg)
kilogram (kg)
kilogram (kg)
kilogram (kg)
atmosphere
atmosphere
atmosphere
bar
bar
bar
Pascal
Pascal
Pascal
gallon (UK liquid)/minute
gallon (UK liquid)/minute
gallon (UK liquid)/minute
metre3/minute
metre3/minute
metre3/minute
By
Flow
0.00378541
0.83267386
3.785412
0.00454609
1.20095038
4.546092
0.001
0.26417203
0.21996915
1000
264.172037
219.969151
To obtain
metre3/minute
gallon (UK liquid)/minute
litre/minute
metre3/minute
gallon (US liquid)/minute
litre/minute
metre3/minute
gallon (US liquid)/minute
gallon (UK liquid)/minute
litre/minute
gallon (US liquid)/minute
gallon (UK liquid)/minute
The information provided has been carefully checked and is given in good faith, but users should take the necessary steps to ensure the accuracy and relevance to their specific requirements. Webtec Products Ltd. do not accept any liability for
injury, damage or unsatisfactory operation resulting from the construction or use of any machines designed using this information.
kilowatt
To obtain
100,000*
14.50377
100,000*
pascal (Pa)
pound/inch2
newton/metre2 (N/m2)
pascal (Pa)
pound/inch2
bar
0.00001*
1.0*
0.0001450377
pound/inch2
pound/inch2
pound/inch2
horsepower
horsepower
horsepower
horsepower
horsepower
By
101,325
14.6959
1.01325
bar
newton/metre2 (N/m2)
pound/inch2
0.06894757
6,894.757
6,894.757
foot-pound/hour
foot-pound/minute
ounce
pound
ton (long) UK
ton (short) US
tonne
ton long (2240 lb) UK
ton short (2000 lb) US
tonne
0.004546092
4.546092
0.003785412
3.785412
0.06102376
Multiply
Multiply
35.27397
2.204622
0.0009842064
0.001102311
0.001*
28.34952
0.02834952
To obtain
To obtain
kilogram
kilogram
kilogram
kilogram
kilogram
ounce
ounce
By
Pressure and Stress
(550 ft-lb/s)
(550 ft-lb/s)
(electric)
(metric)
(UK)
watt
watt
watt
watt
watt
watt
watt
Power
By
0.0003766161
0.02259697
bar
newton/metre2 (N/m2)
pascal (Pa)
To obtain
watt (W)
watt (W)
0.7456999
745.6999
746.*
735.499
745.70
kilowatt (kW)
watt (W)
watt (W)
watt (W)
watt (W)
2,655.224
44.25372
0.001341022
0.001340483
0.001359621
0.001341022
3.412141
foot-pound/hour
foot-pound/minute
horsepower (550 ft-lb/s)
horsepower (electric)
horsepower (metric)
horsepower (UK)
Btu (International Table)/hour
1.341022
Viscosity
horsepower (550 ft-lb/s)
Multiply
By
centistoke
0.000001*
metre2/second (m2/s)
metre2/second
metre2/second
1,000,000.*
10,000.*
centistoke
stoke
pascal-second
pascal-second
1,000.*
10.*
centipoise
poise
poise
stoke
0.1*
0.0001*
pascal-second (Pa.s)
metre2/second (m2 /s)
centipoise
0.001*
To obtain
pascal-second (Pa.s)
* Where an asterisk is shown, the figure is exact
Hydraulic Equations
Hydraulic Motor or Engine Torque
Imperial
T=
5252 x HP
rpm
T=
9.545 x P
rpm
T
= Torque in newton metre (Nm)
P
= Power in watts (W)
rpm = Engine speed in revolutions
per minute
EXAMPLE: What is the torque of an engine
that develops 40 HP at 2500 rpm?
EXAMPLE: What is the torque of an engine
that develops 30,000 W at 2500 rpm?
5252 x 40
= 84 lb-ft
2500
Imperial
Metric
T
= Torque in pound foot (lb-ft)
HP = Horsepower
rpm = Engine speed in revolutions
per minute
T=
Hydraulic Motor Torque Required
T=
9.545 x 30,000
= 114.54 Nm
2500
ST =
Metric
VW x u x r
R
ST =
VW x u x r
R x 101.97
VW = Vehicle weight over driving
tyres (lbs)
VW = Vehicle weight over driving
tyres (kg)
r
r
u
R
= Coefficient of friction of tyres on
average road surface,
generally 0.6
= Rolling radius of loaded driving
tyre in inches
= Overall gear reduction in both axle
and transmission
u
R
= Coefficient of friction of tyres on
average road surface,
generally 0.6
= Rolling radius of loaded driving
tyre in millimetres
= Overall gear reduction in both axle
and transmission
Designed and produced by the Marketing Dept.
CONVER-ED-ENG-1445.pdf (01/05)
Overall Gear Reduction
Hydraulic Motor Speed from
Ground Speed
rpm =
168
rpm
r
R
=
=
=
=
S
=
Imperial
168 x R x S
r
Factor
Revolutions per minute of engine
Rolling radius of loaded drive
tyre in inches
Overall gear reduction including both
axle and transmission
Vehicle speed in miles per hour
EXAMPLE: Find the motor speed where the
overall gear reduction is 10, vehicle speed is
15 mph and rolling radius of driving tyre is 15
inches
rpm =
168 x 10 x 15
=1680 rpm
15
Imperial
Metric
R=
2651.51 x R x S
rpm =
r
168
rpm
r
2651.51 = Factor
rpm
= Revolutions per minute of engine
r
= Rolling radius of loaded drive tyre in
millimetres
R
= Overall gear reduction including both
axle and transmission
S
= Vehicle speed in kilometres per hour
R
S
EXAMPLE: Find the motor speed where the
overall gear reduction is 10, vehicle speed is 20
kph and rolling radius of driving tyre is 400
millimetres
rpm =
168
rpm
r
R
S
rpm x r
168 x R
= Factor
= Revolutions per minute of the motor
= Rolling radius of loaded driving tyre in
inches
= Overall gear reduction including both
axle and transmission
= Vehicle speed in miles per hour
EXAMPLE: Find the mph of a vehicle where
the motor speed is 1680 rpm, the rolling radius
of loaded driving tyre is 15 inches and the
overall gear reduction is 10
S=
1680 x 15
= 15 mph
168 x 10
Imperial
Metric
S=
rpm x r
2651.51 x R
2651.51 = Factor
rpm
= Revolutions per minute of the motor
= Rolling radius of loaded driving tyre
r
in millimetres
R
= Overall gear reduction including
both axle and transmission
= Vehicle speed in kilometres per hour
S
EXAMPLE: Find the kph of a vehicle where the
motor speed is 1326 rpm, the rolling radius of
loaded driving tyre is 400 millimetres and the
overall gear reduction is 10
S=
1326 x 400
= 20 kph
2651.51 x 10
= Factor
= Revolutions per minute of engine
= Rolling radius of loaded driving tyre in
inches
= Overall gear reduction including both
axle and transmission
= Vehicle speed in miles per hour
R=
Ground Speed from Motor Speed
S=
R=
EXAMPLE: Find out overall gear reduction of a
vehicle where the motor speed is 1680 rpm, the
rolling radius of loaded driving tyre is 15 inches
and the mph is 15.
2651.51 x 10 x 20
= 1325.75 rpm
400
Imperial
rpm x r
168 x S
Axle Torque
Ta = T x Rta x Ra
Ta = T x Rta x Ra
Ta
Ra
Rta
= Axle torque (lb-in)
= Axle gear reduction
= Gear reduction through
auxiliary transmission if used
= Motor torque (lb-in)
EXAMPLE: What is the rear axle torque in
high gear on a vehicle having 1000 lb-in
motor torque, an auxiliary ratio of 4:1, and
an axle ratio of 20:1
Ta = 1000 x 4 x 20 = 80,000 lb-in
Metric
Ta
Ra
Rta
= Axle torque (Nm)
= Axle gear reduction
= Gear reduction through auxiliary
transmission if used
= Motor torque (Nm)
EXAMPLE: What is the rear axle torque in
high gear on a vehicle having 100 Nm in
motor torque, an auxiliary ratio of 5:1, and an
axle ratio of 20:1
Ta = 100 x 5 x 20 = 10,000 Nm
1680 x 15 =
10 to 1
168 x 15
Metric
rpm x r
2651.51 x S
2651.51 = Factor
rpm
= Revolutions per minute of engine
r
= Rolling radius of loaded driving tyre
in millimetres
R
= Overall gear reduction including
both axle and transmission
S
= Vehicle speed in kilometres
per hour
EXAMPLE: Find out overall gear reduction of a
vehicle where the motor speed is 1680 rpm, the
rolling radius of loaded driving tyre is 381mm
and the kph is 24.
R=
1680 x 381
= 10 to 1
2651.51 x 24
Hydraulic Pump Formulae
Actual Pump delivery (lpm) = Volumetric efficiency (max. of 1) x Displacement per
revolution (lpm) x Pump speed (rpm)
Volumetric efficiency
=
Actual Pump delivery
Theoretical Pump delivery
Hydraulic power (kW)
=
Pump delivery (lpm) x Max. pressure (bar)
600
Torque efficiency
=
Overall efficiency (max. of 1)
Volumetric efficiency (max. of 1)
Input power (kW)
=
Hydraulic power (kW)
Overall efficiency (max. of 1)
Torque at pump shaft (Nm) =
Hydraulic power (kW)
62.83 x Torque efficiency (max. of 1)
The information provided has been carefully checked and is given in good faith, but users should take the necessary steps to ensure the accuracy and relevance to their specific requirements. Webtec Products Ltd. do not accept any liability for injury, damage or unsatisfactory operation resulting from the construction or use of any machines designed using this information.