Eaton recently discontinued its Hydraulic Launch Assist system, which combined a hydrostatic hydraulic drive with a mechanical drive running in parallel. The hydraulic drive engaged when a heavy vehicle encountered frequent starting and stopping (as in refuse collection routes), whereas the mechanical drive engaged for longer-distance and highway travel.
Eaton's Hydraulic Launch Assist hydraulic hybrid system was said to offer energy recovery of up to 80%, and fuel savings on the order of 4 to 5 gal/day for refuse trucks and a retrun-on-investment of 2½ to 5 years.