The Twin Cyclone Bus Vacuum System 


Robertson Air Systems is the original designer of the highly effective twin cyclone bus vacuum system. These systems have been successfully installed in bus maintenance facilities throughout the United States for the past twenty-five years.  State-the-art technology as well as innovative solutions in custom design are utilized to meet the specific needs of each transit  facility.

The twin cyclone bus vacuum system offers advantages over other bellows-bus vacuum systems as follows:

  • More vacuum power per unit with no dust settling anywhere inside the bus during vacuuming.
  • A more efficient bellows seal (98% efficient on most busses), easily maintainable and extremely durable.
  • Efficient collection into a standard trash container without filters or second handling of the trash.
  • Quiet operation--83 dba on the fuel lane while vacuuming and 79 dba with the bellows retracted.
  • Efficient dust free collection into a standard trash container without filters or cartridges.

Click here to view specifications for the above equipment.

General Operating Instructions:

  1. The bus is positioned with the front door in line with the bellows
  2. The bellows mounted "start" button is pressed to turn on the system and start the bellows extension toward the bus.
  3. The bellows mounted 3/8" blow gun and hose is pulled to the back of the bus while the bellows is moving toward the bus.
  4. Starting at the back of the bus, the blow gun is directed into the corners and under the seats in a manner that forces the dust and litter toward the front door. All items that can be lifted and moved out through the bellows is acceptable and will be collected, separated, and deposited in the compactor/trash container.
  5. When the operator reaches the front door the bellows mounted "stop" button is pressed. The bellows retracts away from the bus, the hose reel automatically rewinds, and the blower is set to time stop after 5 minutes.

Pull Through Blowers and Stack Dampers

The blowers are called "pull through" because they "pull" clean air off the top of the cyclones instead of "push" trash laden air into the cyclones. Pull through blowers are more aerodynamically designed (efficient) than material handling push through blowers and therefore produce more air flow per HP. These blowers can produce up to 30,800 cfm at 50 HP. The blowers are connected respectively to both cyclone discharge openings and connected respectively to both discharge openings and mounted through-the-roof as shown. The through-the-roof configuration offers advantages as follows:

The stack dampers are mounted respectively on each blower discharge opening and close during bellows retraction. They offer advantages as follows:


Atomizing Misters

Atomizing misters have solved the microscopic dust emissions problem. The misters emit microscopic water droplets into the air stream carrying bus trash and dust particles into the cyclone. The water particles attach to the dust particles (50 to 10 microns in size) and cause them to separate from the air being discharged from the cyclone. Tests in the Seattle Metro North Base Facility show that the misters reduce dust emissions by 76%.

Each atomizing nozzle has a pressure regulated water and air connection. Different water and air pressure settings vary the droplet size, spray pattern, and water volume.


Long Body Cyclones, Sonac Sensors, Access Doors, and Compactor

The new long body cyclones are even more efficient than the earlier model twin cyclone assemblies and will separate out 99% of all debris and dust down to 50 microns even without atomized misters. In addition, the cyclones are mounted with sonac sensor high level detectors (located approximately 18" above the base as shown) that will sense paper back-ups which can occur if the trash container is not dumped on time.

Cyclone access openings are also provided to allow easy clean outs.

The air tight 3 HP compactor (optional) compacts the trash into a standard 2 cubic yard container. The container can easily hold one week of compacted vacuumed trash. The trash container detaches from the compactor during dumping. The containers can be custom built to accommodate any trash hauling service dump truck.

The cyclones can also discharge trash directly into an air tight 3-cubic yard dumpster.



The Robertson Air Systems bellows bulkhead and louvers are constructed of 14 gauge sheet metal. The louvers and top seal leading edges are mounted with spring loaded rubber seals. The rubber seals will bend to the contour of the bus when the bellows is extending against it. All the bellows components are heavy duty constructed to endure the rigorous treatment associated with vacuuming busses.

The air piston actuated front and rear louvers open and close to form three different positions--"narrow" "wide" and "delay open". The three different positions will seal the door openings of most transit busses.

The hose reel is mounted on the bellows bulkhead backside. The hose is drawn through the front and automatically rewinds by a hose reel mounted air motor.

Robertson Air Systems has designed a new-style bellows that will seal all busses including para transit vehicles (90% seal efficiency for RTS buses--98% seal efficiency for all other busses). Ten new bellows are now in operation for the Orange County Transit Authority at their Anaheim, Garden Grove, and Irvine Operating Bases and the North County Transit District East Division Facility in Escondido, CA.

Please visit our "Projects" Page.

Contact Information

Phone: (714) 420-1450
Fax: (866) 906-1450