I went to an Indy race once on behalf of ComputerVision. I am not a car buff but I have to say that the event was a thrill – from talking to mechanical engineers in the team garages, to watching the pit crew work on sidelined cars, to the race itself. I don’t recall any mishaps on the track while I was there, but when there are crashes at motorsport venues, results can be devastating and sometimes fatal. That’s because a front-end collision during a race often knocks the fuel pump off the engine, which is the primary cause of fire, vehicle destruction, and personal injuries.
To reduce the number of potential dangerous incidences and improve driver safety, Xceldyne Technologies took on the challenge of relocating the fuel pump to the trunk of NASCAR racing cars. This location would make the cars safer for the driver and the rest of the race vehicles.
During a race, the cars typically move at over 200 mph, while the engine generates over 800 hp of torque. In the past, a front-end collision would often rip the fuel pump from the engine block allowing fuel to spew all over the hot engine. This created a high risk of fire, not just in the engine compartment but in the cockpit.
Racing teams have been strongly urged to reconfigure fuel pumps into the new location. It is expected that within the next year there will be 100% compliance among all racing teams. The remote fuel pump provides safety by cutting off fuel to the engine during a crash and helps to avoid vapor lock.
According to Kevin Rumley of Xceldyne, “When we got involved in designing our remote fuel pump and flexible drive shaft assembly, there was already a unit on the market. The only problem was that drivers were having a lot of failures, often because the system could not handle the rigorous use that the drive assembly was put through during a race.”
Xceldyne researched the components needed for the redesign and found they needed stronger and more robust parts to solve the failure problems.
S. S. White flexible shafts are available for unidirectional and bidirectional operation in a number of standard sizes and lengths.
Rumley and the team at Xceldyne selected S. S. White Technologies flexible shafts as the key component in their remote fuel pump solution. The flexible shafts used in the racing industry are called cables. They are highly engineered torque transmitting devices manufactured and tested on state of the art equipment. S.S. White’s largest market is aerospace where their flexible shafts are used to actuate jet engine thrust reversers and flap and slat wing control surfaces on many aircraft.
For the fuel pump application, S. S. White Technologies designed a custom flexible shaft that is unidirectional, can withstand long operation under extreme torques and speeds, and rapid acceleration/deceleration, and is available with a specially, custom designed casing that is environmentally tough and can operate under the harsh racing conditions seen in a NASCAR competition.
One of the advantages of the S. S. White flexible shaft assembly was that the interconnects included a locking system to prevent disengagement failures that had previously occurred due to the high vibrations present during a race. “We design using SolidWorks CAD software and were able to work closely with S. S. White in the creation of the flexible drive shaft assembly mating components,” Rumley says. The couplings were also supplied with ball bearings, which are typically used for both high speed operations and applications where there are greater loads.
The casing is necessary for shaft lengths that exceed eight inches, and is also recommended when the environment is dirty, dusty, or corrosive, or when the shafts are run at high speeds as in the NASCAR vehicles. The casing holds the grease in the assembly and keeps dirt and dust away from the rotating shaft. It also guards against potential injury from the rotating shaft coming into contact with someone.
The S. S. White Technologies fuel pump flex shaft drive system not only provides safety, but also helps to prevent vapor lock.
S.S. White created two basic flexible shaft lengths for the application dependent on where the cable is installed. If the shaft is driven off the oil pump, the drive shaft assembly length is approximately 122-in. On the other hand, if the drive shaft assembly is driven off the camshaft they only need a 98-in. flexible shaft. In both situations, the fuel pump is safely mounted in the trunk of the car where it is less likely to break loose and provide a potential hazard.
NASCAR is an endurance application for the assembly, even though the shafts only rotate in one direction. The custom designed mating components to the shaft make it easy to replace the fuel pump if it fails during any part of the race. Because the flexible shaft comes completely assembled, it takes less than 10-min to install.
SS White Technologies
Filed Under: Automotive, Safety systems + components, Software