PIKE LAKE AND EASTERN
HARTFORD SHOPS
STANDARD 14
LOAD CALCULATIONS
REVISED 06/01/03
The following calculations sizes the drive system for a locomotive.
A) ______ lbs Operating weight of engine
B) ______ lbs Total weight of cars
C) ______ lbs Total weight of passengers
D) ______ % % of steepest grade
E) ______ ft Radius of sharpest curves on grade
F) ______ lbs Total train weight = A + B + C
G) ______ lbs Rolling resistance = F x .006
H) ______ lbs Curve resistance if E = 35 ft to 45 ft H = F x .008
if E = 45 ft to 60 ft H = F x .006
if E = 60 ft to 90 ft H = F x .005
if E greater than 90 ft H = F x .003
I) ______ lbs Grade resistance = D x F x .01
J) ______ lbs Total train resistance = G + H + I (tractive effort required)
we ignore wind resistance and accretion
K) ______ Coefficient of friction – wheel on rail, range 0.1 to 0.3
we assume 0.25 for dry rail, 0.1 for wet rail
L) ______ lbs Weight on powered drivers
CHECK L x K must be greater than J
M) ______ in. Drive wheel diameter
N) ______ in Drive wheel circumference = M x 3.1416
P) ______ MPH Desired travel speed
Q) ______ in/min Travel speed in inches per minute = P x 1056
R) ______ RPM Wheel rpm = Q / N
S) ______ lb-in Total axle torque required = (M / 2) x J
T) ______ HP Total hp required at wheels = ( S x R) / 63025
STANDARD 15
STEAM LOCOMOTIVE CALCULATIONS
REVISED 06/01/03
The following calculations sizes the drive system and boiler for a locomotive.
A) ______ lbs Weight on drivers (standard 14 L )
B) ______ lbs Drive wheel diamater (standard 14 M )
C) ______ MPH Desired travel speed ( standard 14 P )
D) ______ lb-in Axle torque required ( standard 14 S )
E) ______ lbs Tractive effort required (standard 14 J )
F) ______ in Cylinder stroke 2 x crank pin radius
G) ______ in Cylinder bore (enter if known otherwise calculate)
H) ______ PSI Boiler pressure
I) ______ in Drive wheel circumference = B x 3.1416
J) ______ in/min Travel speed in inches per minutes = C x 1056
K) ______ RPM wheel rpm = J / I
L) ______ HP HP required at wheels = (D x K ) / 63025
M) ______ PSI Mean Effective Pressure (MEP)
IF 85% cutoff = .98 x H
80% cutoff = .97 x H
75% cutoff = .96 x H
60% cutoff = .88 x H
N) ______ PSI Average cylinder pressure = M x efficiency
efficiency = 75% (losses in boiler piping)
P) _____ in Calculated cylinder diameter
CHECK G must be larger then P
Q) ______in/min Piston speed = K x F x 2
CHECK Q should be less than 3600 in/min
Boiler
R) ______ sq in Grate area = E / 3.5
S) ______ sq in Tube area = R / 8
T) ______ sq in Stack area = R x .06
U) ______ in Nozzle area = R x .005