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Tramac’s TraPac Plate Keeps Contractors Out of Trenches

Wed May 10, 2000 - Northeast Edition
Construction Equipment Guide

Job-site safety involves a lot more than hanging posters and repeating slogans. To lose it can be disastrous on many levels. To improve it, benefits everyone. When working in trenches it is just good common sense to keep men out of them as much as possible. Tramac’s hydraulically powered boom-mounted vibratory plate compactors make the compaction of backfill in trenches safe because a man never enters the trench.

Tramac’s TraPac hydraulic plate compactor, can expand job-site effectiveness of an excavator or other carrier. Contractors today are not just digging with their backhoe machines. They are scaling, rolling, tamping, shearing, breaking, drilling and crushing. Tramac’s mission, with the attachments it offers, is to help a contractor turn a boom machine into a veritable iron “Swiss Army Knife.”

Four Models Fit All Sizes of Carriers

Tramac offers four sizes of boom-mounted compactors to effectively fit all categories of carriers from small, medium and larger tractor backhoes and loaders to mini, medium sized and very large excavators.

Model for Model, These Units Produce More

When comparing models in weight and carrier size categories, Tramac TraPac compactors produce, in some classes, as much as twice the compaction force. This is a function of the size of the housing, the eccentric weight and the amplitude.

Providing such production in a relatively small package has been accomplished only after extensive field testing and numerous improvements. Tramac’s TraPac compactors are not just “attachments for backhoes,” they are authentic compaction machines, sized and powered precisely for the type of work they will be performing. These are boom-mounted compactors designed by engineers with long careers in the compaction industry.

By offering a variety of hydraulic motors, which produce the same output but operate on different hydraulic flow, Tramac TraPac compactors are easier to adapt to any existing plumbing, or match the requirements of other attachments to be run by the same machine.

The most critical maintenance precaution with a boom mounted plate compactor is to keep the eccentric bearing constantly lubricated. Tramac’s units are the only ones on the market today to feature a bearing that is immersed in a continuous oil bath.

Conventional units require manual greasing. With TraPac lubrication it is taken care of and there is no need to depend on the equipment operator to lubricate these machines.

Extra Heavy-Duty Construction

Tramac engineers have made a painstaking effort to examine the design and performance of these units in precise detail. The designs produced today are the result of extensive evaluation and improvements. The units are constructed of high alloy abrasion-resistant steel for maximum durability and dependable operation. Vulnerable areas have been strengthened with oversized materials. Tolerances are religiously inspected and demandingly held to requirements that have been determined from job-site experience.

For example, the eccentric bearing housing is a disk that not only holds the bearing, but the motor is bolted to it as well. It is within this disk that the motor shaft is splined to the eccentric shaft. This important disk is mounted to the side plate of the eccentric housing with, press-fit tolerances. Because it must withstand the powerful vibrating forces of the spinning eccentric weight, it is critical that the press-fit tolerances be maintained so the disk will not be allowed to move.

Tramac engineers have not only dictated that the tolerances be consistently held, but have designed a back up system of collets surrounding the disk to double insure its ability to move. There are numerous such precautions in the design and construction of Tramac’s TraPac boom- mounted compactors.

Oversized Rubber Isolators

Machines that employ the vibratory method of compaction are distinguished by their high frequency of blows per minute (around 2,000). Each rotation of the eccentric shaft generates a stress wave which travels into the ground. This vibration sets the soil particles in motion. The soil breaks down and the particles are rearranged. As the particles rearrange themselves, they force out the air trapped between them and fill the voids.

Obviously when the vibrating compaction machine is mounted, there must be a method of preventing the vibrations from traveling backward up into the boom and carrier. All boom-mounted compactors utilize rubber dampeners or vibration isolators of various designs to protect the carrier from the harmful effects of these unwanted vibrations. These rubber isolators are subject to premature failure from heat and deformation. All boom-mounted compactors are plagued with rubber failure either through operator abuse or just plain fatigue.

Tramac engineers have experimented with various sizes of rubber isolators. The suppliers of these rubber isolators have recommended certain sizes as adequate. Based on field experience, Tramac engineers have elected to choose a size or two larger than what has been recommended. The results have confirmed it. Tramac rubber isolators are now giving an extended lifetime.

Base Plates Sized to Fit the Smallest Trench

Base plate size is often used as competitive comparison. If a contractor asks the base plate dimensions, the salesmen will usually answer, respectfully, “What size do you need?” This is because when designing these compaction plates, Tramac engineers recognized the important need to fit into confined areas. Consequently, all of Tramac’s compactors are fitted with base plates of the most narrow width possible. The base plate comes pre-drilled with bolt holes so that if a larger surface contact is required, it is just a simple matter of bolting on a steel plate with the required dimensions.

The best transmission of the compactors vibrating forces into the soil is achieved when the eccentric housing is welded directly to the base plate as opposed to bolting it on. Bolted-on base plates also have a tendency to loosen. A base plate that is welded to the eccentric housing will not loosen.

Tramac offers built-in swivel-tops on some units and pin-on swivel-top adapters for all. With a swivel-top, the compactor can be precisely positioned. It is not necessary to frequently re-position the carrier. When compacting backfill along a retaining wall, some operators prefer to pull the swivel locking pin and allow the compactor to follow the wall.

Can Be Used as a Driver

There are many driving applications where a Tramac TraPac Compactor is a good choice. This low cost vibrating machine transmits its vibrations into the pole, post or pile being driven, breaking the surface friction and, when combined with a small amount of boom down pressure, allows the post to easily slip into the soil. This economical method of driving has its greatest applications in light sheet pile work, agricultural posts and pier pilings in sandy bottom lakes and bays.

For more information, call 800/526-3837 or visit

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