Rammax makes its name in trench roller compactors - Rammax Maschinenbau GmbH

Diesel Progress North American Edition, June, 1999 by Jonathan Walker

In the global construction industry, the name Ammann is exceedingly well known in the compaction equipment markets. But one of the Swiss company's 20 subsidiaries, in its compaction division, can go a step further. Like Hoover is to vacuum cleaners, Kleenex is to tissue and Band-Aid is to bandages, the name Rammax - as in Rammax Maschinenbau GmbH, of Metzingen, Germany - is synonymous with trench roller compactors in many parts of the European and American construction industry.

This degree of product identification is usually reserved for the inventor of the product concerned, and so it is with Rammax, which has been part of the Ammann group since 1995. "Rammax's founder, Heinz Schutt, developed the world's first trench roller compactor and presented it at the Bauma construction equipment show in Munich in 1971," explained Alexander Greschner, production manager at Rammax.

"As the name says, a trench roller is used to compact soil being refilled into a pipe or cable trench. The origins of this type of machine lie in the tendency of normal plate compactors to dig into clays and other clinging soils and stick fast. This often led to trenches being refilled not with the soil taken out, but with sand and other less clinging materials at extra expense. Using four padded steel drums with skid steering, a Rammax machine is able to keep moving on any type of surface while compacting the soil beneath it under its own weight and the force of its vibrating rollers."

With a patent on the method of supplying hydraulic fluid to the wheel motors through bores in the solid steel vertical frame member between the compaction rollers, Rammax held a monopoly position until the patent expired in 1987.

"At the 1991 Bauma show, 14 other companies were showing off their Rammaxes, but with 16 years' head start in product design and application engineering we have managed to retain 60 percent of the world market," Greschner noted.

Among other key market share statistics, Rammax also maintains a 50 percent share of the important U.S. market, to which 50 percent of the company's total production of around 1200 machines per year is exported. The Metzingen works employs around 130, producing Rammaxes and the company's other major product line, rammers of which some 2000 are produced annually.

In total, Rammax produces five models of trench roller comprising (in ascending order of size) three walk-behind, four drum skid-steer machines, two ride-on, four drum skid-steer machines and two ride-on machines with pivot steering and optional pusher blade. The inclusion of the pusher blade is symptomatic of the recent change in user expectations from these machines.

"More and more, the term trench roller is giving way to the term 'universal compactor' as operators find new applications for our products," Greschner said. "Rammaxes are now used extensively for compacting earthworks in general and particularly embankments and slopes, as well as for reinstatement, refilling and backfilling. Refuse compaction at landfill disposal sites is another task our machines are frequently called to fulfill. As a result of the embankment and slope applications, our performance data now include figures for gradient climbing capability with and without vibration, as well as traditional key data like working width, compaction speed, and static and dynamic linear loading."

Overall, Greschner noted, Rammax products cover working widths from 16 to 56 in. and dynamic loading up to 65 lb./in. They can typically handle gradients of up to 40 to 45 percent with vibration or up to 55 percent without vibration.

In terms of powertrain, all Rammax skid-steer machines follow the same basic pattern. The engine drives three tandem-mounted gear pumps. One of the pumps provides power to the eccentric shaft vibratory device mounted in the center of the chassis.

Each of the two remaining pumps supplies two of four Danfoss high-torque/low-speed gear motors driving the four compaction rollers. To achieve steering of the machine, one pump supplies the two left-hand drive motors and the other pump the two right-hand drive motors. All functions are controlled by manual and solenoid-controlled directional valves. The eccentric shafts are of Rammax's own design and manufacture and use either SKF, FAG or Koyo bearings. On smaller models, a centrifugal clutch is used to ensure that the machines can only be operated when sufficient engine speed and torque are available.

In the larger pivot steer RW 1800 and RW 3000 machines, this arrangement is modified by the addition of a fourth gear pump for the pivot steering cylinder and the use of three variable displacement, straight axis axial piston pumps - one on one side of the single front roller and one each on the rubber-tired rear wheels.

The four pumps are arranged as a pair of twin tandem pumps and driven from a splitter gear via a flexible coupling. The additional pump drives the steering system cylinder and dozer blade cylinders. One pump drives both of the rubber-tired rear wheels, another the single axial piston motor on one side of the roller. On the other side of the roller, the fourth pump drives the eccentric shaft that is located within the roller.