The multi-car Richard Childress Racing team, led by Kevin Harvick (29) has one of two gear
When teams at any level of racing need new equipment or resources, they normally approach one of their sponsors for help. When Richard Childress Racing's NASCAR teams-which field cars for drivers Kevin Harvick, Robby Gordon, and Jeff Green in Winston Cup and Jay and Johnny Sauter in the Busch Series-needed a gear break-in dynamometer for their shop, they did just that. RCR sponsor Rockwell Automation not only delivered the goods for Childress, they did so over and above what you might expect.
When building a set of rear-end gears for most racing applications, the RCR team member assigned to build the gearboxes will assemble the gears to tolerance and then run them under load on this test bed to break them in. Then the assembler will examine the pattern produced by the meshing of the gears to verify that the gears will last the entire race. This break-in machine is also called a dyno because, while the gears are being run, a measurement is taken to find out how much power is required to "drive" these gears. This is very important because, as more power is required to drive them, less is available at the rear tires for acceleration. The amount of power required is a direct indication of the friction in the gear and bearing assembly.
Friction turns into heat over the course of a run. If the gears are too tight, the friction will cause the gears to fail during the race. If the gears are too loose, they will wear excessively and chew themselves up during the race.
It is easy to see why a team would want to have a gear dyno in its shop. The problem encountered by RCR was that there was only one gear dyno in North Carolina, where most NASCAR teams are based. The machine was located at Tex Racing in Ether, a well-respected gear and transmission shop in its own right (Tex Powell, its founder, is a charter member of the Circle Track Technical Council). But, there were economic reasons to bring the break-in machine in-house. Tex Racing's shop was more than an hour's drive from the massive RCR compound in Welcome, adding travel and shipping time to the mix. Additionally, Tex Racing charges $200 to break in a set of gears. One RCR crewman's full-time job was to assemble and break in the gear sets for each car for each race. RCR has five teams, and each team needs to have six sets of gears for each race ... at $200 a shot, that's $6,000 per race. Even taking into account volume discounts, that's kind of expensive even for NASCAR teams when applied over a normal 38-race season.
Early in 1999, a group of RCR engineers, led by Paul Flury, began working on their own in-house gear dyno. A look at the concept of the gear dyno shows that the machine is relatively simple in design, but as the RCR engineering team learned, it was rather complicated to get a working model that met all of their needs. The actual working structure of the gear dyno has a rear-axle assembly mounted behind a powerful engine to drive the differential. Resistance-providing units are then attached to the axle flanges so the road-resistance load can be simulated in the gear set. These resistance providers can take many forms, but might be most easily thought of as a fluid pump pushing against a pressure head. The computers to this assembly control the input engine speed and measure the power required to drive the gears, and the heat of the gear oil in the unit.
After working on their gear dyno for most of the year, the RCR engineers set aside their design because they weren't satisfied with the results. RCR General Manager Bobby Hutchens called on Rockwell Automation because of the company's knowledge of industrial automation. In late December 1999, several Rockwell Automation engineers met with RCR engineers to figure out how to go about designing the dyno with parts and technology available from Rockwell.
This is the gear dyno as it sits in RCR's shops.
The computer controls show what is going on inside the beast.
A closer view of the dyno shows the axle housings and the drive motor (left).