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Vac-Con’s PD Combination Machine is easy to operate, safe, durable and outperforms the competition. All backed by Power Up customer support, and our dedicated dealer network brings more power to you. Using standard hydrostatic drive, this design can power PD blowers up to 27” Hg with ease. With water systems up to 3000 psi and 120 gpm, available filtration, excavating, T.V. and Hi-Dump options, this is truly a “go anywhere, do anything” machine.
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Positive Displacement Blowers
Positive Displacement Definition: To lift a given volume for each cycle of
operation.
History
• The machine was first invented as a more efficient water wheel. Made of wood, it was put in the millstream and as the water flowed through it, the rotors turned and power was generated for milling from the output shaft. It worked well except for a minor flaw; the wood would swell up and ruin the clearances and the mill would stop. The unit would be taken out of service and dried out, shrinking the parts to their original dimensions.
• In an effort to speed up the drying, as soon as the rotors would turn, a power source could be connected to the output shaft and the rotors spun. Someone noticed that such an arrangement would move a quantity of air and the use as an air blower was begun.
Warranty
• The blower is warranted by the manufacturer (Roots, Hibon) and supported by a blower dealer for a period of 1 year. The warranty covers defect of material or workmanship. A failure of any type, the blower must be removed from the truck and shipped to the blower dealer or manufacturer
Failure to repair cycle and typical down time
Customer
Vac-Con Dealer
PD blower dealer
Blower manufacturer
Customer
1 week minimum
Determine cause of failure and submit findings to manufacturer for approval
3 weeks typical
Manufacturer approves warranty and dealer orders parts for repair.
Intake rotation
Must have tight tolerances
Must maintain tight tolerances to move material
Exhaust rotation
P.D. Blower Construction
Drive gears
Driven bearings are shimmed to 9 thousandths (.009) of an inch to center the lobe in the housing
Drive gearOil slinger
Shim plate
Bearing
Spring washer
Fluid seal
Vacuum seal
Drives the lobes
Lubricates gears and bearings
Centers lobes in housingSupports and allows lobes to rotate
Keeps lobes centered
Keeps oil in gear housingKeeps vacuum in housing and stops air leaking in
The land is responsible for maintaining the tight tolerance between the lobe and housing. Any material ingested
will wear the land down increasing the distance between the lobe and the
housing decreasing efficiency
Clearance between land and housing is 9 thousandths of an inch
About the thickness of 2 business cards
Close tolerances
• Absolutely must not have any carry over.• Debris body screens absolutely must be in
place.• Final strainer must be in place• Absolutely nothing larger than 9 thousandths
of an inch (.009) can pass through the blower.
• Special care must be taken, if the blower is not going to be operated for long periods of time oil must be applied to the lobes to keep them from rusting together.
Potential causes of damage
• Carryover running through the blower for long periods of time
Severe erosion
Potential causes of damage
• Large debris causing the blower to stop rotation instantly
Housing cracked because of lobes stopping while running
Head plate broke in two
Potential causes of damage
Over heating caused the lobe to grow (expand) too much causing lobe to head plate contact. Over heating is caused by a restriction or vacuum relief (kunkle) valves failing.
Vacuum relief valves