FARGO, N.D. – Exhaust gas exiting a conventional turbocharger retains tremendous unused energy.
Rather than waste it, New Holland uses this energy to extract extra power from the engine while reducing fuel consumption in its new 9050 tractor.
The first stage of the New Holland Turbo Compound system functions like any other turbo system.
Exhaust gas drives a turbocharger that forces more atmospheric air through the cooler and into the combustion chamber, creating more horsepower.
This setup has been in widespread use for decades.
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At this point in the energy flow, design engineers channel the waste exhaust to a second in-series turbocharger, which they call the power turbine. It spins at 52,000 rpm.
Realizing that the combustion chamber already has all the atmosphere it can handle, jammed in by the primary turbo, the engineers decided to use the mechanical energy of this secondary rotating power turbine to help drive the engine’s rotating crankshaft.
While transferring spinning energy from one shaft to another seems simple at first glance, the engineers knew it had to be smooth to prevent engine damage and to make sure the tractor didn’t gallop or bog down.
Their big challenge was to reduce 52,000 rpm from the power turbine down to the crankshaft range of 800 to 1,800 rpm without shock-loading.
They used a series of reduction gears along with a hydrodynamic energy transfer device called a Voith
coupling.
This fluid coupling absorbs bumps, hits and slumps between the power turbine and the crankshaft.
The Voith coupling is widely used in marine and industrial machine drives, where it’s necessary to transmit power without shock loading. It can best be described as a fluid flywheel, much like an automobile torque converter.
New Holland says the Turbo Compound system creates a fuel efficiency gain of three percent. It is only available on the Cursor 13 engine in the 9050.
The two conventional turbo versions of this 24-valve, 12.9-litre engine are rated at 385 hp and 435 h.p.
With the Turbo Compound, that figure jumps to 485 h.p.
Power take-off rating is 429 h.p. Power growth at 1,800 rpm is 49 h.p. Peak power at 1,800 rpm is 534 h.p. Torque rise is 40 percent. Peak torque at 1,400 rpm is 1,801 foot pounds.
