In between the 400--hp pure production dozers and the under 100--hp finish models lies the mid--size dozers. The role of these units continues to evolve with advances in controls and drivetrain technology.
“These dozers have not traditionally been used for fine grading,” says Brett Errthum, John Deere. “But more contractors today are finding they can be used for fine grading.”
This is driving a trend toward extended track models. “Customers are asking for better grading capability,” notes Errthum. “The easiest way for us to do that is to put a longer track on it.”
Speed And Fine Grading Critical
Rodman Excavating, Frisco, TX, relies on mid--size dozers for fine grading. The company owns 45 dozers, including 31 185--hp John Deere 850s, a few John Deere 750s, plus five Caterpillar D8s, four D9s and one D10. “We really don’t have a use for the small fine--grade dozers,” says Les Foster, senior vice president -- operations.
The John Deere 850s are popular with Rodman Excavating due to the hydrostatic transmission, which is unique in this dozer size class. The hydrostatic transmission matches Rodman’s applications — cutting swales and fine grading building pads. “It cuts them very quickly. Then we can fine grade the pad very quickly,” says Foster.
These dozers are equipped with six--way blades and wide shoes for low ground pressure. “We are fine grading a lot of pads and if it is a little wet, we don’t want to sink in,” says Foster.
When confronted with very tight spaces, Rodman Excavating will rent smaller dozers. However, Paul Herron, fleet manager, points out, “Ninety--eight percent of the jobs can be completed just with the John Deere 850.”
Operators have a lot of input into which dozers they run. “They are the ones out there every day. They have to be comfortable and be able to put that machine to use,” says Herron.
A Versatile Solution
Another contractor using medium--size dozers for a variety of applications is Robinson Paving Co., a Georgia--based firm with an equipment fleet numbering over 200 pieces. “We do a fair amount of grading,” says Darrell Robinson, general superintendent. “I have a couple of jobs right now that each have about 900,000 cu. yds.”
Robinson Paving uses four Caterpillar 621 wheel scrapers and eight Noble 417 pull--type scrapers pulled in tandem by 9000 Series John Deere four--wheel--drive and Caterpillar Challenger tractors.
Its dozer fleet is almost entirely Caterpillar D6 machines. “I don’t think this company will ever move away from a Caterpillar D6 because it is such a dependable machine,” says Robinson. “It has just done such a good service for us.” Yet, the company recently purchased a 190--hp Komatsu D65EX extended track model to supplement its fleet.
Due to the nature of its business, the dozers in Robinson’s fleet need to be versatile to handle multiple tasks. The contractor’s current project provides a good example. “On this particular project, we are running four 30--ton Volvo [articulated trucks] in the same grading operation with the Noble pans,” Robinson explains. “A lot of times, we will put the Komatsu D65EX in the fill area to push the piles from the articulated trucks.”
This machine floats around as needed. For example, Robinson has a Caterpillar D6M slope machine with a wide track. Because there is more slope work on the current project than one machine can handle, the D65EX also gets pressed into a little slope work. “It does well there,” says Robinson.
But the primary task of the D65EX has been in the cut.
The material on this project is mostly clay, but it can quickly turn to sand. “You just run into a band of sand. A lot of times this will be a pretty good--sized area,” says Robinson. “With the pull pans, you will not get quite full pulling through the sand.” The D65EX is used to help push the scrapers. “You get good, heaped loads out of it, especially when we are in just a short cut,” he states.