Ultimate Utility Tractor Test
"Synchronized mesh transmissions are designed to allow smooth on-the-fly shifting of mechanical transmissions under any load condition," says Darr. "These do not allow on-the-fly shifting of the range selector gears, just the speed selector," he notes. "Not only do these transmissions make for more efficient field operations, but they also provide safety benefits in that the operator can downshift smoothly under load to decelerate a tractor when traveling downhill or towing a heavy load."
And since not all synchronized mesh transmissions are designed the same, you should test-drive the tractor to determine the shift quality before making a purchase. This is especially true if you are shifting a lot during use, such as using the tractor for loader work.
The easiest way to examine the transmission's ability is with a simple road test. "Start the tractor from a stopped position, then accelerate the engine and upshift through all the available on-the-fly gears," Darr explains. "After reaching full speed in the highest gear, reverse the process and start to quickly downshift the gears while still maintaining engine speed. A high-quality synchronized transmission will very easily downshift at a high engine speed without any gear grinding."
While none of the tractors evaluated offered full power shift transmissions, several models provided partial power shifting between gear selections within a range, a relatively new feature. The evaluators found the ability to shift between gears an advantage during field applications such as mowing.
An additional transmission option now available on some higher-horsepower utility tractor models is the SynchroShuttle shift. This design allows you to shift from forward to reverse without clutching, which comes in handy when operating front-mounted attachments like a bucket loader or bale forks.
A variation of the SynchroShuttle shift is the power reverse design, which "uses a hydraulic clutch system to very smoothly disengage power to the transmission and change the direction of travel," says Darr. A hand lever located on the steering column, "frees one hand to maintain the bucket controls at all times and eliminates the need to clutch, brake, and shift gears as is required in a standard transmission system," he says.
Types of horsepower
"When comparing the rated horsepower of tractors, you should carefully consider the type of horsepower measurement being stated," Darr informs. Three different ratings are used to define tractor power, including brake horsepower, PTO horsepower, and drawbar horsepower, the most common being PTO horsepower.
"The brake horsepower is that total horsepower that leaves the engine," he says. "The PTO horsepower is a rating of the maximum power available at the PTO shaft if the tractor is stationary," Darr explains. Since only about 80% of engine power will be available at the PTO, knowing PTO rating is important when sizing an implement to a tractor. "Finally, the drawbar horsepower is a measure of the power transmitted through the drawbar to a towed implement," he says.
"You should consider the worst-case operating scenario in order to assure that your tractor will not be underpowered. Consult implement manufacturers to determine the power requirements of specific implements," Darr says.
Evaluators were given the chance to add attachments to the tractors in order to truly examine these horsepower ratings and power requirements.
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