Last fall, Allison Transmission invited a few trade press reporters to Indianapolis to fill us in on a future product: the TC10, an automated mechanical transmission the company will release in late 2012.

We wrote about it for Truckinginfo.com and HDT, but waited to report on the driving experience until the release got closer.

The name TC10 means a Torque Converter with a Twin-Countershaft 10-speed mechanical gearbox. The combination achieves smooth starts and fast shifts and will provide performance and fuel economy superior to that of competitors' products, Allison says.

The product is more properly called TC10 TS (for Tractor Series). It's aimed primarily at short-haul and regional tractors that run on-highway but see a lot of gear shifting, as well as some vocational tractors that don't go off road. It will not replace Allison's fully automatic 4000 RDS (Rugged Duty Series) transmissions that see on/off-road service in straight trucks. The 4000 HS (Highway Series) works well for some heavy on-highway applications but is not a good fit for long-haul road tractors, Allison said.

For our drives, engineers had prepared a pair of Peterbilt 384 daycab tractors. One had a TC10 mated to a 455-horsepower Paccar MX diesel. The other had an Eaton Fuller UltraShift Plus 10-speed with a 425-horsepower Cummins ISX11.9.

We drove the tractors, each pulling a loaded van trailer, on streets and country roads around the south side of Indianapolis. We made a number of stops at traffic lights and arterials and cruised at highway speeds. In demonstrations like these the sponsoring company's product is always better, and sure enough, the Allison was.

One of the TC10's features is very smooth start-ups with the torque converter, and another is quick shifting that's done under continuous power flow - "power shifting," similar to fully automatic Allisons and other products. Power flow in the TC10 alternates among the counter- and main shafts depending on what gear it's in. The TC10 has no dry clutch that contacts the flywheel, but it does have wet clutches: five in the main 5-speed gearbox and two in the 2-speed range box. The range box also uses planetary gears and a synchronizer.

The feel is like an automatic transmission but with less "slush." The result is brisk acceleration. From a dead stop, the TC10's torque converter launched the vehicle authoritatively. The converter multiplies torque to increase the effectiveness of 1st gear's otherwise tall 7.4:1 ratio. The converter locks up at about 4 mph to boost efficiency from there to cruising speed. Ninth gear is 1:1 direct and 10th is a 0.86:1 overdrive. Rolling terrain caused the transmission to shift often between 9th and 10th. Usually I didn't notice unless I looked at the selector's LED readout.

The TC10 always pulled away from its competitor when traffic lights turned to green, but the wins were questionable because the MX engine had more displacement and horsepower than the ISX. One engineer remarked that for comparison purposes, the engines should've been switched, with the TC10 getting the smaller diesel. Even if they had been, however, the Allison still might've won any drag race because of its noticeably quicker gear changing, especially at lower speeds.

While driving the UltraShift I made a left turn against what seemed to be distant oncoming traffic. But the tranny upshifted so slowly that the traffic reached the intersection before I had cleared it, and motorists had to slow down. I was embarrassed because I should have waited. I also blamed the UltraShift, which paused at least 1 to 2 seconds between each shift during which the rig bogged a bit. In fairness, I must say that I've driven UltraShift Plus trannies that were faster, and Eaton says its latest programming makes the gearboxes quicker and smoother. We hope to drive some of those soon.

Still, there always will be some pausing between shifts because that's the nature of Eaton AMTs, as well as Volvo's I-Shift and its sibling, the Mack mDrive, though to a lesser degree. Each power pause causes the vehicle to momentarily lose momentum from which the engine must then recover, burning an extra bit of fuel each time, Allison contends.

Any automated transmission is far easier for a driver to operate than a manual, and if properly programmed, it probably will deliver better fuel economy. It should save enough fuel and eliminate enough driveline repairs to pay for its price premium, though that price might be stiff.

I've heard of Allison automatics listed at $15,000 to $20,000 over a standard manual, and prices for Eaton AMTs often come close to those of Allisons. I've asked Allison people about this, and they say they are taken aback when they see some of the prices, because they sell their transmissions to truck builders for far less.

We don't know what a TC10 will cost against a manual or an Eaton AMT, but it should be somewhat less than a full automatic. It should be available from many truck builders but not all. Volvo and Mack don't offer the UltraShift Plus because they'd rather sell their own automated products, so they're not likely to offer the TC10, either.

Availability and pricing are still uncertain because release is probably six months away, but from this drive I'll say that the TC10 is worth the wait.

From the April 2012 issue of HDT