Evening star., 1923-03-18
CARELESS WASTE OF MOMENTUM
BOOSTS DRIVERS BILL FOR GAS
Excessive Stopping Speeding Up to Point
of Halt and Other Such Practices
Lower Mileage Average

because--as the motorist will dis
cover-the sort of free momentum
which a car acquires i'll coasting
downhill must invariably be KILLED
by application of the brakes for
safety's sake And if the driver is
really careful he will drop into sec
ond." using his engine as brake.
When the engine is being turned
over even with the ignition switched
off, fuel is being wasted in TINS un-
cars excess momentum. This has
nothing to do with conserving mo :
mentum which has been acquired at
the expense OF engine power.
Waste stopping at Curbs.
When a car starts going DOWN.! II
momentum is literally thrust upon H.
and in Sucn generous quantities mat
the driver finds it more of a hin- :
drance than help. But when he is
driving on the level-which repre- =
sents normal cond!tions-cNerE unit
of this force of momentum which mas
been developed at the expense OF en-
gine power can be-and should be-
used to the fullest extent.
Take the matter OF drawing up TO
the curb to stop. Nine drivers out
of ten will keep the engine puilihs
un TO within ten feet of the stopping
potnt--and viii then slam on the
brakes At the moment Of appllca
tion OF the brakes. when the machine
i travelling al fifteen miles an hour,
the momentum Of the car is the prod
net OF it's mass Gts weight times
, its velocity Otis rate OF speed'.
should spare Brakes.
Considered in our popular terms
| for weight and speed the momentum
! of A 3.000-pound car travelling at nj
! teen miles per hour twenty-tw
, feet per second) is $4,000 units The
! brakes are required to overcome thls
! momentum which has been developed
| at the expense OF $4,000 foot pounds
! Of force or 120 horsepower. In other
| words. the actual brake horsepower
! which the car itself would register
| on dynamometer at the moment
!; previous TO application of the brakes
! actually exceed the brake horsepower
! OF the average engine. rms gives the
| reader some idea of what he ls vast
| ing when he dissipates the cars mo
! n1entum Occasionally when the
! brakes fail and the driver goes crash
! ing into another machine he gets
J slight idea of this force of momentum
| In all normal driving. excluding
| instances where the unusual calls
! for quick stopping for safetys sake
! momentum can be used IS the basis
! fer real gasoline economy. When the
! driver reaches n speed cnnsl Stent VIII
traffic conditions. and where the cal
! will roll of its own accord. he should
! turn this force TO profit by dispensing
| with the engine as much as possible
] The idea is not so much to coast
/ but to spare the brakes.
! Many Drivers Careless.
! Most Of the needless stopping is tn,
, result of misjudgment. Drivers speed
up through traffic knowing wei
| enough that they will be obliged tt
! stop at each street intersection ant
/ that the spurts of speed do not hell
them save time. This unsystemati'
/ driving represents a triple waste. be
| cause stopping not only means vast
! of the engines excess power, bu
| waste of the power il expendS In i'm
parting momentum to the car-ant
| brake lining.
The habit of deliberately using tn
! engine to impart excess momentum t.