10 Braking
Page 9
Pro-120 controller instructions
Regenerative motor braking is integral to the Pro
series controllers, but it can be disabled (see section
17). When the demand speed is reduced below the
actual motor speed, the controller starts braking,
returning as much of the braking energy as possible
back into the battery. The rate at which the braking
acts is adjusted by means of the deceleration
adjustment.
For maximum energy recovery, use gentle braking.
Turning the speed control to zero for maximum
braking, shorts out the motor via the relays so there
is then no energy recovery.
Regenerative braking does not work well at slow
speeds, simply because it relies on the motor turning
to provide braking energy. Therefore, if the motor is
only turning slowly it cannot give a lot of braking, so
a vehicle may creep if parked on a hill. To stop this
creeping you can get motors fitted with an
electro-magnetically operated parking brake.
Parking Brake
When power is applied to this, the brake is released
and when power is removed the brake is applied by a
spring. The Pro series controllers have a circuit to
drive such a brake: power is applied to the solenoid
as demand speed is increased above zero and when
the demand speed returns to zero, power is removed.
Parking brake drive is via the 3 pin connector, shown
on the diagram ‘Features’. This should be wired as in
the first diagram.
The 3rd pin is battery negative so you can use a 3
position switch to give Release—Brake—Normal
(brake override facilities), as shown in the diagram
below.
The brake driver will give 1 amp: if more current is
drawn the controller will shut down.
A B C
Release
Brake
Normal
To brake
1
A
B
C
shown in the ‘Connections’ diagram (page 7). For
variable cutback, you could fit a variable resistor. Or
you could use a switch to enable/disable the feature.
The level at which it works is controlled by the value
of the external resistor.
The controller cannot know the difference between a
flat battery and losses caused by very high battery
current in wiring that is too thin, so in some
applications it may have undesired effects. It can be
disabled completely by linking out the pinstrip
marked UVP on the features diagram. Spare
‘jumpers links’ are available from 4QD (
JLK-001
).
9.06
Reversing switch
Reversing switch connections are shown in the
diagram (facing). Reversing is ‘dual ramp’ which
means that, if the vehicle is reversed at speed, it
automatically slows down under control of the
deceleration ramp then, at zero speed, reverses and
speeds up under control of the acceleration ramp.
Whenever the vehicle is in reverse, a speed reduction
circuit operates, so that (if the gain adjustment has
been set up sensibly) full reverse speed is half of full
forward speed.
9.07
Half Speed Reversing
As supplied, reverse speed is half of forward speed.
If reverse speed reduction is not required it can be
disabled by moving the ‘jumper’ on the pinstrip
shown in the diagram on page 4.
9.08
Dual Ramp Reversing
It is possible to disable the ‘dual ramp’ when
reversing becomes ‘pre-select’ so that, if the reverse
switch is operated at speed, nothing will happen until
the demand speed is reduced to zero. Reversing will
now occur when the demand speed is turned up
again. In this mode a push switch can be used for
reversing: push the switch as you move the speed
control from zero to temporarily engage reverse and
release it when the vehicle is moving. Then, when
the speed control is again reduced to zero, the
controller will drop back into forward automatically.
To disengage dual ramp, remove the header
indicated on page 4.
