One of our netters sent me a drawing of a mechanical system which simply
turns the Thomas pump into a dual duty pump. The parts price in Canada
is $96. This should translate into about $60.00 US. The switch could be
easily made by installing a "spool valve". The valve could be mounted on
the dash, probably down by the emergency brake. The valve consists of a
5 port body which the 4 air lines an a filter would be hooked up to. A
slide valve, manually operated, not electric, will direct the air flow
where you wish. While the knob is pulled out the air flow will travel
from the compressor to the air tank as pressure. If your engine ever
quits all that would be required will be to push the knob in. This will
redirect the air flow to be drawn from the booster and exhausting it out
the filter inlet valve. The valve that I checked out is made by a co.
called Norgren. The part no. for this valve is K71DA00-KCO-KK1. These
are three separate parts. The valve body, the valve itself, and the
knob. A contact switch will be added to the leading edge of the knob in
the valve body which will over-ride the pressure switch and start the
compressor to create vacuum. The drawing I received looks very simple to
accomplish and may cost me about $120 to complete the modifications. The
vacuum line on the brake booster is "t" eed in the same as adding a
secondary vacuum pump from some other vehicle. Darren
turns the Thomas pump into a dual duty pump. The parts price in Canada
is $96. This should translate into about $60.00 US. The switch could be
easily made by installing a "spool valve". The valve could be mounted on
the dash, probably down by the emergency brake. The valve consists of a
5 port body which the 4 air lines an a filter would be hooked up to. A
slide valve, manually operated, not electric, will direct the air flow
where you wish. While the knob is pulled out the air flow will travel
from the compressor to the air tank as pressure. If your engine ever
quits all that would be required will be to push the knob in. This will
redirect the air flow to be drawn from the booster and exhausting it out
the filter inlet valve. The valve that I checked out is made by a co.
called Norgren. The part no. for this valve is K71DA00-KCO-KK1. These
are three separate parts. The valve body, the valve itself, and the
knob. A contact switch will be added to the leading edge of the knob in
the valve body which will over-ride the pressure switch and start the
compressor to create vacuum. The drawing I received looks very simple to
accomplish and may cost me about $120 to complete the modifications. The
vacuum line on the brake booster is "t" eed in the same as adding a
secondary vacuum pump from some other vehicle. Darren
