innovations CASTING
Driving Tractors More Effi ciently W
hen hydraulic systems maker Sauer- Danfoss, Ames, Iowa, needed to reduce hydraulic oil pressure drop and improve fuel effi ciency, a compact dual yoke casting from Brillion Iron Works, Bril-
lion, Wis., provided the solution. T e transmission compo- nent was built for use in row-crop tractors. Its function is to vary the speed ratio of an infi nitely variable transmission (IVT) using hydromechanical power split technology. Hydromechanical power split transmissions (HMT) were
developed to improve emissions and fuel effi ciency, an ever increasing demand amid rising fuel costs. HMTs merge the mechanical gear train with an IVT, decoupling the engine speed from ground speed. According to Sauer-Danfoss engineers Eric Jacobson and
Joe Wright, 45-degree bent axis technology has played a key role in the advancement of HMTs in the agricultural tractor market. T e recent dual yoke development further enhances this technology, simplifying the HMT structure and improv- ing robustness without sacrifi cing the low power loss capabil- ity credited to the axis design.
T e original hydromodule assembly for this transmission
included: • Two yokes, a complex casting design that required precision machined features
• A manifold housing high pressure valves • Six high pressure rotary seals, a life-limiting component • Two servo controls with four servo pistons and two spool valves.
T e dual yoke design fi xed the angle so the pumping and
motoring unit displacements are varied simultaneously. In addition, the input speed to the pumping unit varies inverse- ly with the yoke angle. Brillion Iron Works converted the formerly bolted-together assembly of three separate castings into one component cast in ductile iron (80-55-06) using the green sand process with shell and coldbox cores. T is design replaced the two single yokes and manifold
with one part. T e original two yokes weighed 60 lbs. each, and the manifold weighed 90 lbs., for a total of 210 lbs. T e 10 x 11.2 x 19.2-inch dual yoke weighs 90 lbs., a weight savings of 120 lbs. Machining time was reduced 50%, and the assembly
costs were lower. Two cylindrical roller bearings were eliminated as well as one servo control and the high pres- sure rotary seals. Shorter passageways for hydraulic oil accounted for reduced flow losses, aided by the elimina- tion of 90-degree bends in its path. “Internal pressure is half of hydromodule design,” said
Brillion executive Paul DeFlorio. T is design cut the pressure drop in half. Its shape also allowed for a lightweight, high stiff ness design that enabled it to be packaged tightly within the transmission, maximizing the use of available space. Visit
www.brillionironworks.com for more information.
This dual yoke replaced three separate, assembled castings as one part.
50 | METAL CASTING DESIGN & PURCHASING | Mar/Apr 2013
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60