RV FEATURE
its maximum torque at zero rpm. That low-down
torque enables it to take off from traffic lights
much like that Ferrari!
A caravan tow vehicle essentially needs torque
(turning force) to restart the rig on a steep hill,
and keep it going in deep sand. That torque can be
multiplied (at the expense of speed) by selecting
a lower gear.
To put that into perspective, that QLR’s Chevrolet
‘Stovepipe Six’ engine had less power than my
Suzuki Jimny, but could traverse steep sand better
than any other 4WD I have owned, apart from my
700 cc twin cylinder Porche-engined Haflinger.
A huge truck’s engine has enormous torque at
low engine speed – but less power than many an
up-market sports car.
That vehicle’s maximum speed is a function of
its power – in essence to have a lot of torque
at high engine speed. That power will thus
determine how fast it can climb a hill. If laden as
specified, however, its ability to do so, and stop
and restart, is assured.
QLR ACROSS THE SAHARA
One brilliant example is the 1940 QLR Bedford that
I used for crossing Africa (including two 3000 km
Sahara crossings). It weighed over 7000 kg when
its 1500 litre fuel tanks were full. It was powered
by a 3500 cc petrol engine of 72 hp (54 kW). It
had an often-needed bottom gear of 101:1 that
enabled it to climb almost anything and traverse
deep, soft sand – but at only walking speed.
On the return Saharan run, it towed a broken-down
(5 tonne) Forward Control Jeep most of the way.
Collyn Rivers is an ex-research engineer with
a particular interest in RVs. He has written
extensively on most technical matters relating to
the field, from solar to caravan weight distribution
and more.
His website is a trove of reliable information for
RVers, including more on electric vehicles.
VISIT RV BOOKS
RVBOOKS.COM.AU
Collyn Rivers crossed Africa in this 1940 QLR Bedford.
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