The sun. [volume] (New York [N.Y.]) 1916-1920, 1919-07-20
ROAD RESISTANCE
OF TRAILERS FOUND
Proper Methods for Utilizing
These Cost Cutting Ve%
hicles Told.

\ A factor OF prime Importance IN the
development Of transportation over the
highways is the trailer. Unquestionably
the trailer has come to stay, says the
b. f. Goodrich Rubber Co., and its use
and importance will multiply as the ma
tion's roads become improved. So
economical has the trailer proved in
many lines OF haulage that every opera
tor Of motor trucks should carefully
enalyse his delivery in view of adopting
traiiers.
From the farmer who bitches two
wheeled gig to the rear OF his auto
mobile and speeds away with ten cans
OF milk to make the o'clock train, to
the contractor who hauls forty tons OF
crush ed stone in traiers with one motor
trucks power. business men everywhere
are realizing that the principle Of the
trailer Is sound.
The average we'll built truck Is able
to haul behind II three or four times
as much as It can carry. A striking
example Of the efficiency Of the tractor
powers OF a motor truck was demon
etrated by an Eastern street commits
sioner recently who conducted an expert
ment to cut down the cost Of collecting
and hauling garbage from the city to
the disposal plants.
Regular horse drawn wagons were
used to collect the garbage from the
districts. brinsing II to a designated
place, where the horses were unhtched
and the loaded wagons attached to a
ave ton truck. A load Of four and a
half tons of scrap iron was placed in
the truck body In order to give traction
to the driving wheels. The road travelled
passed under viaducts, around sharp
turns and I'D steep gradeA The total
load including the weight Of the trailers
was twenty-seven tonA The tose
covered q round trip distance of afK
miles and resulted In the city purchasing
trailers and disposing Of moro than hall
OF the horses previously used.
Motor truck operators must bear in
mind. points out the Goodrich Company
that the amount a load which a truck
can haul behind It in trailers depends
upon the condition of the road and the
grade met with. For instance ton
truck loaded to capacity ascending 20
per cent. grade could hardly haul single
empty trailer behind it. so nearly has
fits capacity for drawbar pull beer
reached. But this same ton truck
spinning along the level street could haul
probably "a or even 80 tons.
Many experiments have been con-
Quoted to determine the resistance
offered by various kinds of pavement and
road surface to show the effect on the
operation of the rubber tired motor
truck. The following table gives the
generally accepted results of these In
vestigations:
Road Resistant,
in -bs per ton.
Mnnd Moi ACKNOWLEDGEMENTS
Smooth brick. .......'............'...' 70 20 %
yoor brick. ...'...'......;.'''''''''''. 20 10 '"
soft macadam. ACKNOWLEDGEMENTS.
Ordinary clay road.
Country sand road....................15 $50
Sand inches deep. ...................Z1 us to $40
The effect of grade or incline is de
termined automatically. A ] per cent
grade requires l per cent pull. For ex-
ample truck with a gross weight O.
ten tons driven up a grade of pei
cent. will require a force Of six-tenths O
a ton, or 1900 pounds. For each pc
cent. OF grade to be encountered draw
bar pull of / per cent Of 1000 pounds
IS required, or a drawbar pull OF q
pounds for each ton.
When road resistance and resistance
due to grade have been computed. the!
must be added together in order to Civ
the total resistance offered by the gtveI
haulage condition. Say ga ton truck
weighing ~ tons loaded, must climb {
4 per cent. grade over an ordinary ella!
road. The resistance is computed a
follows:
lbs.
q. Road resistance. 100 pounds per ton
for ~ tons. ACKNOWLEDGEMENTS. TO
4 Four per cent. grade resist ance, at
100 lbs. for each l per cent......... 600
1850
In other words itfequires nearly lao
pounds OF drawbar pull to carry the trucl
up this incline over a country clay road
Compare this condition with that of thu
level asphalt street. where the total re
sistance would have amounted to 10
pounds