Adjustments Can Make Or Break Your Regenerative Air Sweeper Fleet

Operators are usually responsible for the daily sweeper upkeep, such as washing, servicing, and inspection of the sweeping components. An untrained eye may miss critical inspection points and may not be aware of the adjustments needed to make the sweeper operate more effectively and efficiently.

Routine inspections and adjustments are required to keep a sweeper fleet on the road sweeping and out of the garage. Water is a vital component to the life and longevity of any vacuum sweeper’s components. Water suppresses dust, adds weight to the debris so it filters or falls out of the airstream more completely, and acts as a lubricant so that the vacuumed debris is less abrasive to the wear items. Many an impeller has succumbed to “carryover”—debris that remains in the airstream—because an operator continually operated the sweeper without refilling the water tank or didn’t do a daily check to see if the spray nozzles in the suction head were plugged.

With regenerative air sweepers, the air stream is contained so it is not vented or exhausted into the atmosphere. Containing dust, dirt, and debris—also known as “the three D’s”—is vital to the function of a regenerative air sweeper. There are several variations to a regenerative air sweeper; one variety is the “standard” configuration that is used for most municipal applications, streets, parking lots and some alleys. Balance or suspension of the pickup head is an important piece of this sweeper’s ability to capture and contain the three D’s.

Before the airstream is generated, the pickup head can be balanced or suspended. Dropping the pick-up head into its operating position and pulling forward several feet will allow any curtains to fold back and let the pick-up head drag into its normal operating position. Take a measurement from the lowest point of the pressure slot opening, to the bottom of the dirt shoe. The proper measurement should be 1-inch to 1 ½-inch to the bottom of the dirt shoe skid. Watch out for manhole covers if more than 1 ½-inch high. This adjustment will ensure the pressure slot opening—sometimes referred to as the “J” plate—has sufficient clearance from the sweeping surface so it will not be damaged.

At this point, the pick-up head’s dirt shoes should be floating ¼- to ½-inch off the sweeping surface. This suspension is accomplished by four, six, or eight springs distributed around the pick-up head at each corner. The pick-up head’s configuration, standard head, runway head (airport applications) or equipped with a center broom, will determine the number of springs. It can be impossible to balance a pick-up head if the pressure side of the head is filled with caked-on dirt, which adds weight to the head. This is another reason the pick-up head must be removed periodically to be thoroughly inspected and cleaned. When the vacuum system (airstream) is active, this slight float will limit dirt shoe wear as the pick-up head makes contact with the sweeping surface. Normally, the pick-up head only has contact when the vacuum system is at sweeping RPMs or speeds. The corner springs support the weight of the pick-up head, allowing it to “float” on the road surface.

Several areas will require inspection, adjustment, and service on a regular basis. Occasionally, the pick-up head should be removed to perform a thorough inspection of the pick-up head curtains. Once the head is out from under the sweeper, turn it over and take note of the condition of the curtains. Any rips, tears, holes, missing sections or deformations will require replacement. Curtains are vital to the sweeper’s ability to seal the pick-up head to the sweeping surface, ensuring the debris under the head will remain there to be conveyed to the hopper. Any discrepancies in the curtaining will allow the blast air from a pressure slot to blow material out from under the head, creating a dust cloud as the sweeper travels down the road sweeping.

The pick-up head is built in two pieces. One side receives the pressurized air flow from an air pump of some kind, commonly an impeller. This “pressurized” air flow must be metered and directed to create the optimum discharge into the “vacuum” side of the pick-up head to dislodge stubborn debris that has adhered to the sweeping surface. The discharge is commonly controlled and metered through a “pressure slot” with specific dimensions to best utilize this airflow, stream or blast, or what we like to call a full-width “air knife.” Check with your sweeper manufacturer to get the specifications regarding your adjustments. Factory specifications provide general setup for “most” applications. If the pick-up head is still lacking in the desired performance, the pressure slot openings can be manipulated as a trial-and-error process to maximize the blast air’s performance. If this step does not enhance the performance of the head, return all adjustments to the factory recommendations (normally a 3/8-inch pressure slot opening).

Another component common to regenerative sweepers is a “vacuum enhancer” device—usually a small door or flap in the pressure tube that will divert some air or let it escape for specific applications, creating more vacuum to pick up sand, leaves or other fine debris. Diverting the incoming air from the pick-up head leaves only vacuum under the head, which enhances the vacuum for fine or light debris applications. Most municipalities are faced with leaf-sweeping applications late in the year. Operators, mechanics and sweeper manufactures all suggest removing a forward curtain (the heavier of the two) and using the vacuum enhancer to capture leaves more effectively without blowing them out from under the pick-up head. It also reduces the chance to “plow” the leaves in front of the head.

The sweeper configuration includes an auxiliary engine, fluid coupler for pure vacuum machines, drive pulley, drive belt and airstream generating device. Neglecting the auxiliary engine—or PTO if the airstream is managed by PTO—will often require an engine replacement. Inspection and service intervals are published by each engine manufacturer. Service the auxiliary engine in accordance with the engine manufacturer on “severe duty schedule”. Tensioning of the drive belt is important to extend the life of the belt. Some manufacturers use a fluid coupler, some a direct drive, while others may use a closed-loop hydrostat to power the impeller. If a belt is used, tensioning of the belt will be performed by a tensioner and torque method or a deflection versus pounds to deflect. Regardless of the method used, proper belt tension will keep the vacuum system up to manufacturer standards. Slipping belts due to lack of maintenance become glazed and must be completely replaced. Regular inspection and serving will significantly reduce belt replacement costs.

Regular impeller inspections will ensure long life and prevent any significant equipment failures. An inspection is required any time a vibration is noted during sweeping operations. Vibration can come from debris in the impeller or missing weights. For impeller inspections, remove any access door or plate to allow access and rotate the impeller (refer to the safety section in the operator and service manuals). Never start the auxiliary engine or engage the vacuum system when opening the impeller housing. And be sure to lockout/tagout any piece of equipment that puts you in harm’s way while performing inspection. Look for erosions of the end plate and vanes, missing weights used to balance the assembly, knife edges and debris accumulations. If the housing has a liner of any kind, make sure the liner is firmly attached or glued into the housing. If the liner is shredded, be sure to inspect the outer diameter of the housing for damage from any debris that may be thrown out against the housing. Any damage or perforations to the housing usually require replacement. A repaired housing may not be able to hold a liner afterwards. Bearings used to support the impeller must be serviced with a high-temp, extreme-pressure grease like Shell Retinax NLGI Grade 2 lubricant.

Elgin Sweeper, the leading manufacturer of street sweepers for general street maintenance, special industrial and airport applications, offers ongoing maintenance classes on the company’s regenerative air sweepers to operators and technicians. Too many times, sweepers are not cared for in a responsible manner. The longer the equipment neglect goes unresolved, the worse the sweeper performance.

For more information on regenerative air sweepers available from Elgin Sweeper, please contact your local Elgin Sweeper dealer, or visit www.elginsweeper.com to find a dealer near you.

Sold and serviced through a network of more than 100 dealer locations worldwide, Elgin Sweeper products are the sweepers of choice for a variety of general street maintenance, special industrial and airport applications. With more nearly 100 years of experience, Elgin Sweeper offers municipalities, contractors and industries the most sweeper options in the country, using the latest sweeping technologies—mechanical, pure vacuum, regenerative air, alternative fuel and waterless dust control. Elgin Sweeper is a subsidiary of Federal Signal Corporation’s Environmental Solutions Group. For more information, visit www.elginsweeper.com.

Story by Jimmy Broyles, CBT supervisor, ESG University, Elgin Sweeper