OVER/UNDER DRIVE
Dual Range® Auxiliary Transmissions
NOW YOU DON'T HAVE TO CHOOSE BETWEEN POWER AND ECONOMY
AMERICA'S MOST POPULAR AUXILIARY TRANSMISSION
Truck Parts Specialists is Proud to Offer you the US Gear line of Quality Performance Products. When it comes to your Families and your Equipments Safety, rely on the Experts at Truck Parts Specialists to supply you with US Gear's fine products. D-CELERATOR UNIFIED TOW BRAKE, D-CELERATOR DIESEL EXHAUST BRAKE, CYCLONE POWER FAN, DUAL RANGE AUXILIARY TRANSMISSION, TORQ-LINE GAUGE KITS, AND THE TORQ-LINE CHROME TURN DOWN TAILPIPES.
Application Chart & Price
- Functions Exactly Like a 2-Speed Axle
- Available as Underdrive or Overdrive
- Strongest Guts in the Industry Proudly
Made in the U.S.A.
Gear Ratio Chart
Changes in the Towing Industry
Over the past decade, automotive manufacturers have incorporated major power and performance enhancements to both gasoline, and especially diesel powered vehicles. In fact, many of these specialty engines have an amazing amount of torque under the hood. Some vehicles on the overUnder hand, are designed to simply provide good economic value. From the factory, your vehicle should be equipped to give you either the power you are looking for, or the economy you need. In the real world however, it's not that simple. There are times when you really need the extra power; like when pulling heavy loads. Then there are overUnder times when you really need the fuel economy; like when cruising at high speed with no loads. It is for this reason that US Gear offers TWO DIFFERENT AUXILIARY TRANSMISSIONS; AN UNDERDRIVE UNIT OR AN OVERDRIVE UNIT, MADE IN AMERICA. No overUnder manufacturer in the industry can make that claim.Why Two Different Units?
From the factory, your vehicle comes with only one rear-end ratio. So what happens when sometimes you're heavy and in need of those extra low end gears to get you up and moving while overUnder times you're light and need the higher gears to get you moving faster and more economically? The fact is that one extremely low gear ratio does not offer the gear selection necessary to provide both low speed power and high speed economy. And what about the times when you're at high speed and suddenly need just a little more power, but don't have enough gears to comfortably get any. Conversely, if you are at low speed and suddenly need to be moving quicker, there's simply no way to make it happen. To keep the engine in its maximum power range, Dual Range offers twice the number of different gears to easily move you to the closest gear necessary for your immediate needs...all with a push of a button.
The overdrive unit gives you twice as many higher gear ratios than you originally had for more pulling performance, while the underdrive gives you twice as many lower gears for that extra power you need to get your weight moving easier with less throttle. Whichever unit you choose, you will improve economy, and decrease wear and tear on the engine. So which one is right for you? Let's take a look at the different issues specific to motorhomes, trucks and vans.
Specific Truck and Van Issues
Trucks and vans that pull trailers, whether gas or diesel, automatic or stick, are distinctly different from motorhomes, because their loads can be dropped. This means that sometimes you'll be heavy while overUnder times you'll be light. And because your engine produces its best power in a narrow rpm range,you will need the flexibility of numerous gear ratios to keep it running in the "sweet spot". If you own a newer model truck with an automatic transmission, chances are it came standard with an overdrive. But if you are towing really heavy loads, the OE overdrive may be too high even with the tremendous horsepower and torque produced by the engine. Even the original equipment manufacturers tell their customers NOT to pull heavy loads with it. Under this set of circumstances, you will need to add the Dual range to either replace, or lower the factory overdrive ratio to give you the power and economy you are looking for.
By selecting the proper Dual Range unit to complement your existing gear ratios, you can finally enjoy both low speed power and high speed economy. Our tech department can help you decide what is right for your set of circumstances.
Specific Motorhome Issues
Gasoline powered motorhomes with automatic transmissions are extremely heavy and continuously get heavier as amenities such as slide out rooms, washers, dryers and even the family sedan are added. They already come equipped with an overdrive providing the needed high gear ratio, but don't have low gear ratios for climbing the hills quicker and with less throttle; not to mention engine retarding for coming down the hill. Throw in the fact that you can now drive faster due to speed limit increases, and you've really got some complications. You obviously need a Dual Range underdrive unit. And by adding this low range unit, the factory transmission becomes a real pleasure to use. Not only do you gain the pulling power so useful for towing, you're actually able to use that power in the factory overdrive mode.
How To Use The Dual Range
Nothing could be easier! An electronic control module mounts directly to the gear shift lever and permits precise control of the Dual Range Auxiliary Transmission. While the unit is electronically controlled, you will hear it shift mechanically as do big over-the-road commercial trucks. And it's this simple; keep the unit in the low range position when you are driving in mountainous regions or when heavily loaded, and shift to high when you're cruising on the interstates. Or, you can shift the Dual Range as you're shifting the primary transmission to split your existing ratios.
And the Dual Range Is a Real Work Horse
From the very beginning; the Dual Range was designed for towing extremely heavy loads. With a GVCW rating of 35,000 lbs and a torque capacity of 2000 ft lbs, the Dual Range has the strongest guts in the industry. It was specifically designed to use in either 2-wheel or 4-wheel drive, forward or reverse, both uphill or downhill compression braking, and at any speed. There simply is no limit to how and when to use the Dual Range. Again, no overUnder auxiliary transmission manufacturer can make that claim.
Applications Available
Pick-ups, vans, cab-chassis, class C or the very popular class A motorhomes, two-wheel or 4-wheel drive, We've Got Them All! We are adding popular new applications as soon as they become part of the towing world, so stay tuned!Call our technical support department; tell them what you have and what or where you feel you need improvement. Chances are, they already have a solution.
