Which Gearbox Should I Learn?...
You have decided that you want to get your truck licence, the next question is then what gear box should you learn to drive?
There are a number of factors that come into making that decision, but first let’s look at the three options.
(AKA Crash box, unrestricted, constant mesh)
All the above names describe the un-restricted gearbox with the most common brand being the Roadranger and these gearboxes come in a 9, 13, 15 or 18 speed, depending on the truck and application.
What makes this gearbox different is that the driver has to match the road speed (KM) and engine speed (revs) to enable a gear change to take place. These gearboxes require more driver input to ensure that you are able to change gears smoothly or at all. This process is called doubling the clutch. (Double declutch)
This is not to be confused with the gearbox having a high and low range lever, as these come in both constant mesh and synchromesh forms.
So when changing gears in basic terms this is how it’s done:
- Accelerate to the appropriate road speed.
- Clutch in.
- Out of gear into neutral
- Clutch in to select the correct revs
- Clutch out
- Clutch in
- Select next gear at appropriate revs approx1500 rpm Clutch out
- Slow to the appropriate road speed eg for 5 low 25 kph
- Clutch in
- Our of gear into neutral
- Clutch out
- Rev engine to appropriate revs approx. 1400 rpm
- Select next gear
- Clutch out
The road speed and revs required changes, depending on the road conditions, e.g. going uphill or downhill.
Every truck used to have this type of gearbox, however they have become less common over the years as new technologies have been developed however they are still common in a large number of heavy duty trucks particularly US trucks.
The main advantage of this gearbox is its simplicity, strength and durability. Almost any truck mechanic repaired this type of gearbox as it is common across a number of brands of truck. The strength comes from there being no synchro’s so there is more metal delivering engine power to the road.
From a drivers point of view there is a lot more to think about and do when driving this style of truck with the big thing being to plan what you are going to do i.e. what gear to select and give yourself time to make the gear change. Many drivers do prefer this type of gearbox as it gives them more control and are rewarding to drive when you get it right.
If you get your licence with this gearbox you will be allowed to drive this gearbox and the Synchro/Automatic types, ie you will have an UNRESTRICTED licence.
(AKA Standard Single Clutch Gearbox, B Restriction)
ie HR-B, HC-B, MC-B,
The main difference between this and the constant mesh gearbox is there is no need to double the clutch as the gearbox has synchro rings which match the road speed and the engine speed so the gear can be changed. This takes the job away from the driver.
A significant number of trucks come with this type of gearbox as it is easier to drive than the roadranger gearbox. It comes in a variety of shift patterns from a standard 5 or 6 speed to a 12 speed with range change.
Most round town trucks doing local deliveries, such as those run by Toll or Linfox use this type of gearbox as it is easier for the driver to operate and there are more potential employees.
If you get your licence in this style of vehicle you will not be licensed to drive the Crash gearbox (roadranger), as this is a restricted licence to driving Synchromesh & Automatics ONLY.
ie – HR-A, HC-A, MC-A,
More and more trucks are being purchased with an automatic transmission as the technology has improved significantly over the last 10 years. They range from the small round town delivery trucks to the interstate B Doubles and road trains.
Some trucks are a two pedal auto ie brake and accelerator while others are knows as a three pedal auto have a clutch pedal, the clutch is only used when stopping and starting the vehicle or in some cases the clutch pedal is only used in slow speed manoeuvres such as reversing.
The advantages are the ease of operation and also as the transmission can be programed to ensure the truck is driven with the best fuel economy in mind, which can significantly reduce running costs for major companies over the large number of trucks they have and can save millions of dollars a year for a company such as Toll.
Automatic trucks are different to an automatic car in that they are an automated manual transmission or AMT. This means that there is an auto shifter changing the gears in a manual gearbox. For a driver this means that while it is an auto, you need to allow the truck time to change gears and sometimes you will have to override the transmission and select gears in the manual mode to ensure the truck and safely traverse the route.
Even if you have a manual car licence and you get your truck licence in an Automatic vehicle, you will be restricted to driving Automatic Trucks and Buses only. This is a restricted licence to driving Automatic trucks & buses ONLY.
If you hold an Automatic C Class Car Licence, and you get your Truck Licence in a Manual, you will STILL be restricted to driving Automatic Cars only. You will still be able to drive manual TRUCKS, but not CARS.