Editing Booster engine (section)

==Calculating tractive effort and operating speeds==

A rough calculation of booster tractive effort could be made with the following formula:<ref>{{cite magazine |url=https://archive.org/details/sim_railway-locomotives-and-cars_1929-07_103_7/page/443/mode/1up?view=theater |title=Exhibit "G'—Formula for Computing Tractive Effort of Locomotive Booster |magazine=Railway Mechanical Engineer |volume=103 |issue=7 |date=July 1929|publisher=Simmons-Boardman Publishing Corporation |page=443 |via=Internet Archive }}</ref>

<math display=block>t = \frac {cd^2spr} {w},</math>

where
* ''t'' is tractive effort in [[Pound (force)|pound-force]]
* ''c'' is the coefficient representing mean effective pressure, normally set to 0.80
* ''d'' is the [[piston]] diameter in inches ([[bore (engine)|bore]])
* ''s'' is the piston stroke in inches
* ''p'' is the working pressure in [[pounds per square inch]]
* ''r'' is the booster gear ratio
* ''w'' is the diameter of the trailing wheels to which the booster is geared in inches

The typical locomotive booster employed a pair of {{convert|10|in||adj=mid|-bore}} by {{convert|12|in||adj=mid|-stroke}} cylinders. Available gear ratios and associated operating speeds for both the Franklin type C and type E booster models are detailed in the table below.

{| class=wikitable style=text-align:center
|+ Locomotive booster gear ratios and associated operating speeds<ref name="BoosterTest1" /><ref name="BoosterTest2" />
! 
! scope=col | Gear ratio
! scope=col | Maximum cut-in speed
! scope=col | Maximum operating speed
|-
! scope=row | Franklin Type C-1 & C-2
| 2.571
| {{cvt|12|mph}}
| {{cvt|21|mph}}
|-
! rowspan="3" scope=row | Franklin Type E & E-1
| 2.71
| {{cvt|15|mph}}
| {{cvt|25|mph}}
|-
| 2.25
| {{cvt|18.5|mph}}
| {{cvt|30|mph}}
|-
| 2.00
| {{cvt|22|mph}}
| {{cvt|35|mph}}
|}