GOMACO World Index --- GOMACO World 27.1 - January 1999
A GOMACO Dowel Bar Inserter (DBI) was first used in 1983 by Kasler Corporation of San Bernardino, California, on a concrete runway at Dallas-Fort Worth Airport in Texas. The process took three machines, as the independent DBI system traveled between two pavers and inserted the bars across the concrete slab.
In 1986, the DBI system was modified to follow the paver alone. There were two oscillating screeds added on the rear of the machine to reseal the slab after the insertion process. Therefore, the DBI paving process went from three to two necessary machines.
By 1987, GOMACO introduced the ability to install the attachment onto a four-track paver rather than having the system follow behind it independently. In order to greatly improve the rideability and production, a computer-control system was added to the dowel bar insertion process. The operator was then able to preset random joint spacing and the machine would repeat the cycle on its own. A patented trolley system was developed that would distribute the dowel bars across the width of the slab into the individual slots of a bar-holding tray.
In 1996, the In-The-Pan Dowel Bar Inserter (IDBI) system was packaged under the paver's standard length. The IDBI system was first used on a two-track GP-4000 slipform paver. This new IDBI was the industry's most productive and compact system for the automatic insertion of dowel bars across a finished concrete slab. The IDBI fits between the tracks and does not require the massive rear extensions to the frame of a paver that previous DBI's required.
Recent improvements have been made to the IDBI system to reduce setup time, simplify controls, and further enhance rideability.
New and Improved IDBI
GOMACO has recently added an oscillating straightedge and redesigned the finishing pan. Production has been enhanced by simplifying the hydraulics on the system. The previous spring-steel bar retainers in the bar-holding tray were replaced with rubber-backed fiber pads. The new pads increase the accuracy and durability of the retainer and greatly reduce the number of adjustments in the setup process.
Installation of a new digital speedometer has aided in production by helping to monitor and maintain a constant paving speed. Another new addition is the smart cylinders, which are computer controlled to maintain the accountability of the depth of the bars into the concrete slab. The stopping points of the fork beam assembly were originally detected using a number of proximity switches. The ease of setup has now been enhanced by using more computer controls in conjunction with the smart cylinders, thus eliminating the need for proximity switches.
New touch screen controls allow the operator to select the number of pavement lanes which will have bars. There are new troubleshooting and diagnostic capabilities added that were not on the previous systems.
This new IDBI attaches to the rear of a paving mold on a GOMACO two-track or four-track paver. The paving operation, bar insertion and finishing operations are all combined into one compact unit. This process eliminates manually setting bars in baskets on the grade prior to paving operations and allows concrete supply trucks to dump directly onto the grade. It eliminates the need for another piece of equipment to do the task and provides bar placement after vibration and consolidation of the concrete.
Currently there is a project underway in Eads, Colorado, by Lawson Construction Company. Some of the photos in this article are from that location.
GOMACO holds the United States and European patents on the bar-loading trolley and In-The-Pan DBI (IDBI).