How they did it....

• By using an artificially long 1 200 m (¾ mile) course consisting of flat terrain, Deere intentionally engineered the study to suit the 748H. There is no measure of initial power or torque, strictly pulling. Once the load is moving, the steady pull takes less power and as such, the power shift transmission will be more fuel efficient. In real logging, starts and stops are frequent and skidding distances are shorter.

• By choosing a 620C with an inappropriate gear ratio for racing on a track. Tigercat skidders have different gear ratios available for different applications. The deepest gear is appropriate to dual and high flotation tire applications as well as extremely steep or rough terrain. Judging by the the dualing rings and heavy duty axles the 620C is equipped with, it looks like Deere chose to use a 620C with the deepest gear ratio -- most inappropriate for flat ground and long distance skidding.  

• By matching the load size at 8 400 kg (18,540 lb), even though the 620C is capable of a higher payload than the 748H. We don't know exactly what the machines were pulling or how much drag resistance there was. What we do know is that the 620C can be equipped with larger grapples than the 748H. 620C owners who also run or previously ran 748 skidders, routinely tell us the the 620C is capable of larger payloads. 

grapples sizes available:
748H - 1,38 m² (14.9 ft²)
620C - 1,39 m² (15 ft²) or 1,58 m² (17 ft²)
E620C - 1,58 m² (17 ft²) or 1,76 m² (19 ft²)

• By not conducting proper time studies on real logging jobs, on real terrain with real timber.

Go to the Deere website to review the methodology and results of the study and see for yourself. 

Fuel Efficiency

Under real working conditions, where skid distances are typically under a quarter mile, Tigercat’s unique hydrostatic drive system works to reduce fuel consumption in a number of ways:

Variable engine speed

Tigercat skidders utilize electronic control technology combined with Tigercat's hydrostatic drive system.

This allows Tigercat skidders to operate at variable engine rpm. Engine rpm increases automatically only when additional horsepower is demanded.

Infinitely variable gear ratio

Operators need not be concerned with shifting gears to regulate engine speed. Under load, Tigercat skidders smoothly and automatically decrease wheel speed and increase torque for the optimal gear ratio. Can the operator of a power shift machine ALWAYS be in the correct gear?

Energy Recovery

Like a hybrid automobile, a Tigercat skidder puts energy back into the system every time the machine comes to a stop.

More about hydrostatic drive  >>

What do the Customers say?

Jerry Burgess, owner of Jerry Burgess Trucking, Inc., Lufkin, Texas

Jerry owns a Tier II and Tier III 620C. He usually logs in clear cut areas with timber ranging from 30-45 cm (12-18 in) BHD. Each machine produces approximately 17 to 19 loads per day (26-28 tons per load) with skidding distances averaging about 200 m (1/8 mi)

The Tier II 620C uses an average of 18 L/h (4.8 gph). The Tier III uses 21 L/h (5.6 gph).

  The math... Tier III 620C

Based on 8 hours actual skidding

Fuel consumption related to production volume is the right measure...

Mark Burt, owner of Burt, Inc., Warren, Arkansas

Mark Burt runs a Tier III 620C in a very challenging application. According to Mark, "This skidder is working to the max, meaning dual tires, mud to the belly pan and maximum loads all the time. The average skidding distance is a quarter mile." Mark skids full trees with about 45-50 cm ( 18-20 in) DBH and produces 15 to 18 loads ( 26-28 tons per load) per day. His records show fuel consumption of 25-28 L/h ( 6.5- 7.5 gph). IQAN shows 30 L/h ( 7.9 gph).

   The math... 620C

Based on 8 hours actual skidding

Fuel consumption related to production volume is the right measure...

Mark Kinard, owner of Kinard Enterprises Inc, Ehrhardt, SC

At the request of a Deere salesman who brought Deere 748H and 848H skidders to his job site, Mark conducted a trial similar to the Deere study. He was asked to design a course that would take approximately 15 minutes to complete. Mark laid out a 2 km (1.2 mi) course consisting of flat terrain that initially took around 7 minutes to complete. The machines would lap the course twice for the purpose of the time trials. This is what happened:

1. 748H - 14 min
2. E620C - 13 min
3. 848H - 12 min
and so on....

"The times kept getting faster," says Mark. Because the machines were pulling the exact same load of trees over the exact same terrain, the times got quicker and quicker because drag resistance and weight were reduced on account of limb breakage and a smoothing out of the course itself. Mark explains, "The wood and the track kept getting slicker as the limbs broke off and the times got faster and faster for all the machines." The only conclusion that Mark came to is that such trials are nonsense because they do not approximate real logging. 

However, After the time trial Mark ran all the machines on his job and noted that in terms of capacity, "The E620C and the 848H are real close. The Tigercat could pull drags that the 848 couldn't." 

Mark's E620C pulls 340-355 tonnes (375-390 tons) per day and burns an average of 19 L/h (5 gph).

   The math... E620C

Based on 8 hours actual skidding

Fuel consumption related to production volume is the right measure...

"The E620C and the 848H are real close. The 
Tigercat could pull drags that the 848 couldn't."