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What’s a road ranger gearbox and how do you change gears?

Some trucks (mostly large American and Asian ones) have a non-synchronised manual gearbox made by Eaton. This is commonly known as a Roadranger and they come in various configurations up to 18 forward gears and 4 reverse gears.

How do you get 18 gears from a gear lever?

This diagram, while seemingly complicated, explains everything you need to know about an 18-speed Eaton Fuller transmission.

You’ll see it looks like a regular manual gearbox with H-pattern gate. On the left you have reverse and low (we’ll come back to those), while in the middle and on the right you have the main set of gears you’ll be using for the majority of your driving. They have 1, 2, 3 and 4 written on them, plus 5, 6, 7 and 8.

The white and black colouring in each position represents high and low range, respectively, and in each gear ratio there’s an H and L split (sometimes called overdrive and direct). Overdrive is like a half step between one gear and the next.

On the right, you can see the grey splitter (18-speed units have a grey splitter vs a blue for 15-speed and a red for 13-speed). At the front of the gearstick is the hi/lo range shifter – it’s a black plastic switch that moves up and down. Image courtesy of Andrew Myers

Our basic position will be low range and L split. The gearstick rests in the middle position just to the right of the line between 1 and 2. So, if you push the gearstick slightly to the left and up, you’ll go into gear 1. If you pull it down and slightly to the left, you’ll go to gear 2. If you go to the centre, right and up, gear 3 and so on.

Once you get to gear 4, there’s a switch on the front of the gearstick knob which changes it to high range, so you can go from 4 to 5 (the same position as 1), 5 to 6 (the same position as 2) and so on up to gear 8.

OK, so we have 8 gears of the 18. Where are the other 10?

Each gear has a H and L split positions. So, gear 6 with the split in H is really like gear 6.5, but that actually doubles the number of gears available. Now we’re up to 2×8=16 gears.

The final two gears are on Lo. This is a crawler gear designed for starting off with very heavy loads or going up steep hills. Many drivers never (or rarely) use this gear. 16+2=18 gear ratios or ‘speeds’.

On your reverse gear position you have high and low range as well as H and L split, which gives you four gears. You don’t change range when you’re moving in reverse, only the split.

How do you use the clutch with a Roadranger transmission?

If you’ve driven a regular manual car, it’s quite different. A manual car has a syncromesh gearbox which means you can take it out of one gear and put it into the next gear without having to worry about anything. Non-synchro gearboxes are often called ‘crash boxes’ because that’s the noise you’ll make if you get the gearshift wrong.

Because it’s a non-synchro ‘box, you have to double-clutch. You press the clutch once to enable you to move the transmission out of gear, then once again to enable you to move it into the next gear. The process when changing up is:

  1. Release accelerator
  2. Clutch down
  3. Gearstick to neutral
  4. Clutch up
  5. Clutch down
  6. Gearstick to next gear once the revs have dropped
  7. Clutch up
  8. Press accelerator

The space between pressing the clutch twice is enough for the revs to drop enough to place it in the next highest gear. You are matching the engine revs with the road speed so that the gears mesh seamlessly.

To downshift, the process is almost the same.

  1. Release accelerator
  2. Clutch down
  3. Gearstick to neutral
  4. Clutch up
  5. Blip the accelerator to bring the revs up
  6. Clutch down
  7. Gearstick to next gear
  8. Clutch up
  9. Press accelerator

You’re adding step 5 to match the revs. When you change down a gear, the revs need to be higher, which is why you’ll press the throttle just to bring the revs up slightly and the gear lever will sneak into place.

If you don’t get this right, you’ll find out the meaning of crash box.

Now, when you start driving, you’re bound to get this wrong a lot for the first few hours so remember your hospital pass: fifth gear. You can almost always get a truck into fifth gear even if you badly mangle your gear change. Remember that you’ll need to be in hi range and 5th gear is in the middle and up.

How do you use the splitter?

The splitter is easy to use: while accelerating, you pre-select the next gear using the splitter. As soon as you release the accelerator and press the clutch, the gear will change – no need to move the gearstick.

On the image below, the splitter is red (Eaton has different coloured splitters for different gearbox configurations).

13-speed Road Ranger has a red splitter switch. Image courtesy of Gary Paakkonen

The splitter switch rocks forwards and backwards.

Most drivers will only use the splitter for gears 5-8, unless they’re working in a quarry, off-road, or hauling very heavy loads.

How do you get good at changing gear with a Roadranger gearbox?

This article has given you the basics of how to change gears using a non-synchro ‘box. The next step is for you to do Roadranger training online and then apply that in the cab..

Darren has owned several companies in the automotive, advertising and education industries. He has run driving theory educational websites since 2010.

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