Pulling’s Silent Partner: A Look at the Ironman Sleds
Truck and tractor pulling in simplest terms is a dance between two partners. There’s an animated and loud partner leading the dance, the pulling vehicle. The other partner, the sled, is in full and silent control of the path of the lead, even as it follows. Let’s take a look at the silent partner that graces Freedom Hall and how it’s set up differently from the world of outdoor pulling.
Since 1995, Vaughn Bauer and his team have provided the sleds for the Championship Tractor Pull at the National Farm Machinery Show. Bauer’s Ironman sleds are a prominent part of national pulling events across the United States, with four sleds in action at 200 events annually. While much of their season is spent outdoors, Bauer and his team shift focus and gears, literally, to provide a top-notch dance partner for the Championship Tractor Pull.
On the surface, everything is the same for outdoor and indoor action. The pulling vehicle guides the sled down the track while the weight box moves forward onto the sled pan to increase downforce/friction, ultimately stopping the vehicle. From there, some differences come into play.
The track in Freedom Hall is a shorter course than typical outdoor tracks and in turn the sled must do its job at faster pace; to do that job the weight box is sped up to apply downforce faster. That’s accomplished by a gear change in the Eaton two-speed gearbox driven by the ground drive axle on the sled. That gear change provides the necessary extra speed to move the weight box faster. Between the two-speed and the weight box final drive is a five-speed ProFab transmission that offers incremental speed changes needed for different classes and track conditions. Bauer indicated that second, third, and fourth gears are the primary gears used and ideally produce distance changes of 10 feet between each gear.
Beyond the gearing change there’s an addition to the sled that makes indoor pulling bearable, the smoke tube apparatus. Without the apparatus and the dedicated smoke system permanently built into Freedom Hall, pulling would be unbearable because of the volume of diesel smoke emitted in the popular “smoker” classes. For die-hard pulling fans the addition of the smoke tube assembly would seem to have a dramatic effect on the performance of the sled, but the effect is minimal. Weighing only 700 pounds the apparatus shifts the weight balance of the sled slightly. That change in balance is only noticeable in the two lightest classes at the Championship Tractor Pull, the Modified Four Wheel Drive Trucks and Lightweight Super Stock Tractors. To counteract that change in sled balance, a 2000 pound weight is placed in the back of the weight box to optimize the performance of pullers in those classes.
From there, it’s go-time. A bare, 32,000-pound sled is weighted up at various levels depending on the class in competition. For the Modified Tractor class, a full load of 14, 2000-pound blocks are in use to keep that class in check for a total sled weight of 60,000 pounds. Pro Stock Tractors require 9 to 10 blocks for a 52,000-pound burden for that class to bear. As you watch a class in action, you can take note of the number of blocks in the weight box and determine how much weight is needed to stop the wide variety of classes at the Championship Tractor Pull.
Beyond that, small but important pieces to the puzzle are in play. The pan trip, engaged by the weight box as it travels to the top of the frame rails, forces the pan into the ground even further through hydraulic cylinders. The pan trip typically remains a consistent setting throughout the event except for during the Modified Tractor competition to keep the sports’ most powerful class under control. On the bottom of the sled pan are 14 grousers that aid the pan in digging into the track further. Bauer offered that 240 to 242 feet is the “sweet spot” for winning distances; it’s a subtle step in the “dance” that puts the front tires of the pulling vehicle at the edge of the legendary sand pile in Freedom Hall without diving deeply into the pile.
It is evident after speaking with Vaughn that he enjoys his role of being an integral part of the Championship Tractor Pull. He offers that the efforts are not his alone; it’s a team that makes this portion of the “dance” happen. The team has two parts. There’s the Paton, Iowa-based portion consisting of Vaughn, his brother Kevin Bauer and Chris “Big” Sprecher that handle sled duties. A quartet of “Blue Shirts” from the National Tractor Pulling Championships in Bowling Green, Ohio - Tom Schaller, Don Schaller, Brian Schaller, and Dan Sheldrick round out the team. Hooking and unhooking from the sled are among their primary duties. Should there be any issue with the primary sled, the team brings an additional sled that can quickly be put into action.
During your visit to Freedom Hall for the Championship Tractor Pull, enjoy the power, action, and performance of the elite drivers and machines invited for the five sessions of competition. Remember their dance partner as well and their vital contribution to the sport of pulling.