Triumph TR4 - DRIVING FROM NEW - SPEED AND OVERDRIVE; Speed Limits and Overdrive Unit

DRIVING
FROM
NEW
Whilsi
no
sDecific
speeds
are
recommended
during
the
running-in
period.
avoid
placing
heavy
loads
upon
the
engine.
such ai usine
full
throllle
at low
speeds
or
when the
englne
ls
cold. Runniig-in
should
be
progreisive
and
no harm
will
resull
from
the
engirie
being allowei
to
"rev.''
fairly fast
provided
that
it is LhoroL;ghly
uarrn and
not pulling
hard.-Always
select
a
lower
gear if necessary
to
relieve lhe
engrne
ol load.
Full
Dower
should
nol
be used until
at
least
500 miles
hrve
been
covered
and
even lhen,
il should
be used
only
for short
oeriods
at a
lime. These
periods
can
be extended
as
the engine
6".or"t
tor"
responsive.
After 1.000
miles
running.
the
engine
can
be considered
as fullY
run-in
Recommended
Speed
Limits
Avoid
over-rewing,
Particularly
in
the lower
gears
The
driver
is advised
notlo-drive
the car
continuously
at engine
soeeds
above
1,500 r.p.m
in any
gear.
Houever.
whilst acceleral-
iirs
through
the
gears
it
is
permissible
to at(ain
5.000
r'p m
for
sh"ort
periods,
this speed
being
indicated
by
a red
segment
on
the
taihometer.
When
an
overdrive
is
fitted,
do not
change
from overdrive
to
normal
3rd or
2nd geals
at engioe
speed
exceeding
4,000
r'P m
,
otherwise
damage
may
result
from
"over-revving"
Overdrive
Unit
(when
fitted)
An overdrive
unit serves
as a
convenient
method
ofproviding,
at
will,
a lower
overall
gear
ratio to
reduce
engine speed
and
wear,
and
to
effect
fuel economy.
l4
The Lavcock
de
Normanville
overdrive
unit
incorpor
an eoicvclii
gear
train
which
is engaged.
to gire
overd
conditio'n.
by'a
cone
clulch
moring
under
the
infruence of
hydraulic prissure
generared
by
a small
piston
pump
piessure
is
reteased.
ria
a control
val\e. the clutch
is t
irnd
held
in direct
drive
by compression
sPdngs
A
Top
gear
Third gear
Second
gear
..
Crealest
benefit
$ill accrue
lronr
judicious rrse of lhe
over-
drire.
the
eoverning
factor
being
lhat
the
vehicle continues
lo
run
easily
"withou
t-sign
of engine
labouring.
colnbined.
\
ilh
mounted
on
the steering
colulrrn.
the
minimum
amount-of
throttle
oPening
necessary
to maintain
this condition.
directional
roller
clutch
enables
the
change
into, or
out
overddve
to be
made
when
transmitting
full
Power,
without
of road
speed.
The
hvdraulic
control
valve
is
linked
to an
electro-m
solenoid
rihich
is operated,
via a
relay,
by a two-Position
Suggested
minimum
engagement
sPeeds
are:-
Top gear
. . 40
m.P.h.
Thirdgear
..
30m.P.h.
Ma\imum
disengagement
speeds
are.
-
85 m.P.h.
6l
m.P.h.
45 m.P.h.
The
above
disengagement
speeds
correspond
aPProximatel\
ro
peak revs. in
no-rrial
gear'
Disengagement
of the
O/D al
"oeeds
hieher
than
those
stated
nlay
cause
damage
lrom
"over-rewlng--.