Among the newest asphalt compactor models in the Caterpillar Paving Products range are the vibratory double-drum CB-334E and the combination CB-335E. The two drums on CB-334E are each 51 inches wide, and the machine has an operating weight of 8,731 pounds. It's a machine, says Cat, well suited for rental customers, contractors and public agencies maintaining streets, roads, alleys and recreational paths. The combination CB-335E has the same 51-inch, vibratory drum in the front, but uses four smooth tires at the rear. This 8,092-pound machine is said to take the place of two rollers by providing the benefits of both a vibratory and pneumatic compactor.
The vibratory system for the drums uses a "pod-style" design. The pod, which houses the eccentric weights, is assembled and sealed at the factory to ensure cleanliness, extended bearing life and easy field exchange. The vibratory system, operating at 4,140 vpm, is designed to strike a balance between frequency and amplitude to provide a good mat finish for commercial work, Cat says. The drums, constructed of rolled steel plates, are finished to reduce surface irregularities and feature specially designed edges that assist in eliminating marks on deep lifts and when turning. The vibratory system for the CB-334E provides three settings: front only, rear only or both.
Enclosed within the machine frame is a 79-gallon polyethylene water tank that supplies the drum-spray system, which can be run at a constant rate or intermittently to extend operating time between refills. The water pump, says Cat, is designed for extended life, and a triple-filtration system is aimed at reducing downtime caused by spray-system clogs. A large drain for the tank allows emptying the system in five minutes.
At the rear of CB-335E are four 7.50 × 16, 6-ply smooth rubber tires that are designed to generate a high ground-contact pressure that penetrates deep into the lift. And, says the company, the flexibility of the tires results in developing horizontal pressures that assist with compaction. Each tire is fitted with an adjustable scraper (that can be retracted when not required); and a pressurized, 5.3-gallon tire-wetting system uses a nozzle above each tire to spray solvent on tire surfaces to prevent asphalt pick-up.
Both compactor models are powered by the Cat 3024C liquid-cooled, four-cylinder diesel engine that has a net-horsepower rating of 46.9 and is Tier-II compliant. Both machines also use a variable-displacement hydraulic pump in their propel systems, and both use a separate, fixed-displacement hydraulic motor to drive each drum. The CB-335E uses two motors to drive the rear wheels.