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Spec Master: Crawler dozers

June 12, 2007 |

Length with blade in straight position, without ripper(feet, inches) [position 1]
If the blade is further out away from the machine, you gain some visibility but lose operator response. If the blade is placed closer to the machine, you have quicker operator response but lose some visibility. The total length of the machine also becomes a factor when transporting medium dozers.

Track length on ground(feet, inches)
[position 2
The more track on the ground (fore or aft), the less machine pitch and greater stability. Longer tracks give you a more stable platform and are good for light dozing and finish grading. The additional track length, however, also adds more weight and makes the machine slightly less maneuverable.

Height to top of cab(feet, inches)
[position 3]
Also a transportation issue, especially with medium dozers, which tend to move from job to job and need to clear bridges and other overhead obstacles.

Ground clearance(inches)
[position 4]
This comes into play especially in forestry and pioneering work, where working around stumps and uneven ground is an issue. Another application where this becomes a factor is soft underfoot conditions. The more ground clearance you have, the better chance you have of not getting stuck. This needs to be balanced by machine designers, however, with center of gravity.

Track gauge(inches)
[position 5]
Track gauge is measured from the mid-point width of one track to the mid-point width of the other track. A wider gauge typically gives you better machine performance when working on slopes.

Operating weight with dozer blade and
without ripper(pounds)
Make sure you know which dozer blade is being figured into this since blades can vary in weight. The weight and balance of the machine are critical. Typically more weight and horsepower is required when you need to push heavy loads in a mass production situation. Balancing the front of the machine with either a counterweight or ripper comes more into play when finish dozing.

Net horsepower
Horsepower is usually more critical in heavy dozing, when you’re looking for high productivity. With finish dozing, it becomes a factor in steering. A dozer should have a good horsepower-to-weight ratio. If you have too much horsepower and not enough weight, you’ll spin the tracks, lose productivity and waste undercarriage life. When there’s not enough horsepower and too much weight, the machine will struggle to stay up with productivity demands.

Transmission and drive
Transmission type
Power-shift transmissions have generally taken the lead over mechanical transmissions in heavy dozers, although mechanicals are still used. Power shifts offer less operator fatigue since operators shift with buttons instead of levers. Smaller dozers feature hydrostatic transmissions, which give you infinitely variable speeds and greater maneuverability. Hydrostatic transmissions, however, are more susceptible to contamination, keeping them out of heavier dozers. Torque-divider transmissions are more efficient than torque-converter types, but they also take up more space and are more expensive. Both torque-divider and torque-converter transmissions are seen on heavier machines.