the field artillery journal - Fort Sill - U.S. Army

MOTOR TRANSPORT FOR FIELD ARTILLERY
is damaging to vehicles of rigid construction. Fig. 11 shows a
horse-drawn caisson striking a crossing projecting about two
inches from a smooth road. At fifteen or twenty miles per hour
the jolt would have been worse. This is not a plea for nursing
matériel but the fact that our vehicles are rigid must be
considered and tractor companies whose product is not so
rigid, will not guarantee over six miles per hour and normally
provide a maximum speed of about 4 miles.
For rapid movements over good roads of guns assigned to
anti-aircraft service, to resist landing parties or to other special
rôles of minor tactics, would it not be better to place the gun on
the truck and run it off at the destination? Fig. 12 shows a
German gun so carried and it is understood that the French
have done the same thing quite extensively.
Figs. 13 and 14 show an excellent type of 50-horse power
wheeled farm tractor tested. This machine weighed 8500
pounds and at first appeared very attractive for heavy towing,
but the drawbar pull in bad mud before the wheels began to
spin was only 1500 pounds and it takes 2000 to move a 4.7inch
gun in bad mud. When good footing could be secured the
pull was 4000 pounds without effort and 5000 in low gear. The
following table gives an idea of the capabilities of such a
machine on fair roads.
Grade per cent.
Pounds pull per
ton
Effective drawbar pull
(4000 lbs. less
component of weight
acting paralled to road)
Tons which can be
hauled
Tons which can be
hauled assuming
matimum pull of 5000
lbs. less component of
weight parallel to road
0 175 4000 23
27
5 225 3600 17
21
10 300 3200 11
14
15 410 2700 6 8. 5
20 575 2300
4 6
25 800 1800 2 3. 5
It will be seen that the power is ample for handling a section
of heavy artillery under normal conditions and a gun or
ammunition limber and caisson on grades running up to 25 per
cent., always assuming that the hold on the ground is sufficient
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