Like a car stuck in low gear, logging engines were built for their power and their ability to gain traction on steep grades. Speed was not generally a consideration in the design of these locomotives. Of the 3 major types of geared engines (Shay, Climax & Heisler) however, the Heislers were typically the fastest. This made them a tad more flexible than the other types, because they could be used for off-mountain operations without forcing train conductors to abandon their pocket watches in favor of calendars. The Heislers were also the most efficient of the geared engines because their well-designed drive-trains had half as many gears and bearings as a Shay, so more power ended up being delivered to the driving wheels. Unfortunately, no design is perfect and one of less desirable aspects of the Heisler design is the ride. The V-twin arrangement tends to ride pretty rough. Anyone who has spent a whole day on a Harley Davidson Motorcycle can probably sympathize with Heisler crews. Some crew members at Cass have been known to refer to the days when they are assigned to run the Heisler as "Shay Appreciation Days."