INNOVA Award Winner for the November/December 2003 Issue

The Level Solution to Compaction Challenges

Rammax's new P33-HHMR-BD from Multiquip is a walk-behind roller with a leveling blade.

“Rammax rollers pioneered specialty trench compaction,” explained Multiquip Product Manager Steven Spence. “As this is their primary function, the backfill blade is a natural fit. After a trench is excavated and the pipe work performed the trench is backfilled. Usually the dirt is dumped back into the trench in piles leaving an uneven surface. Ideally, the backfill should be leveled out so there is an even and consistent surface to compact, vital for proper compaction. Previously, workers were placed in the trench with shovels to perform this leveling work or if the trench is wide enough, skid steer loaders are used. This presents two problems: workers were exposed to trench hazards (cave-ins) and in wide trenches a second machine and operator are required, adding expense to the job.”

The P33-HHMR-BD has dual compaction settings that allow the operator to change amplitude, frequency and compaction force making the roller effective in more granular soil applications.

“Dual compaction force settings allow for more compaction variations,” said Spence. “In some situations municipal codes may restrict the depth of backfill (depth of lift) over the pipe while in others it may depend on the type of pipe or the type of trench construction (right-of-way or street cut, etc.). Due to the strength of the maximum compaction force available with the HHMR roller, it may be preferred to lower the compaction force over a thinner lift to avoid damage to the pipe. In addition, consider that lowering the compaction force also raises the frequency (VPM) of the compaction effort and lowers the amplitude. This is more efficient in situations where granular soils are encountered. On the other hand, cohesive soils need to be sheared to compact. This is achieved by using higher force and amplitude.”

The roller also has two drum widths, 33 and 24 inches for maximum flexibility and performance in shored trenches and against trench walls and sides. “The upper main body portion of the roller is designed from a single sheet of formed metal,” said Spence. “This eliminates a lot of the metal panel connections and hardware which has a high proclivity to vibrate loose and fall out.”

Fueled by an 18.5 hp Hatz 2G40 diesel engine, the P33-HHMR-BD utilizes amplitudes of 0.09 and 0.07 inches giving the operator additional flexibility. Frequency options are 1,800 and 2,520 vibrations per minute.

“Rammax has used the same basic hydrostatic drive system for over 30 years. The drive motors are manufactured by Danfoss,” explained Spence. “All four drums have a drive motor attached to them. The unit is steered by 'skidding', similar to a skid steer tractor. Two travel levers control the left- and right-hand movement by using a combination of forward and reverse actions to determine direction. Both levers forward action will drive the roller straight ahead, both levers back action reverses the roller. Positioning the left lever forward and the rear lever back will turn the unit to the right, and vise-versa. The gearing associated with the drive system is manufactured to a very fine tolerance, this is one reason we offer a 5-year warranty for the drive motor assemblies.”

The roller utilizes heavy vibrator and bearings for premium production and extended life with warranties of up to five years on the hydrostatic drive motor assembly, eccentric housing assembly and bearings. The P33-HHMR-BD's fully hydrostatic operation eliminates maintenance on many components and its clamshell design allows easy access to service functions, including the battery that is now located in the front of the machine. The remote transmitter is housed in a concealed storage box for safety and security while allowing the operator to better view the entire diagnostic control center.

“The battery is a wet-cell battery specifically designed by Rammax for this application and manufactured for them by Banner in Germany,” said Spence. “The battery was relocated up front as a convenience to the customer. Previous roller models had the battery located in a rather tight compartment accessed from the rear of the roller. It protected the battery well but made access when jumping a dead battery tricky and impractical; this was overcome by placing electric terminals up front near the engine in case the roller required jump-starting.”
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