1.3.1 Section B Flashcards
B1.1 What is the purpose of the gearbox?
The purpose in a vehicle is to provide a selection of ratios to suit varying road and load conditions.
B1.2 How does a synchromesh gearbox work?
The transmission uses a small hub device, which contains a ‘baulk ring’ and a ‘cone’ which synchronises two gears that are rotating at different speeds.
When the gear speeds are synchronised to the same speed gear, selection is effortless. All ratios in a synchromesh transmission will have a synchromesh hub attached to aid gear selection, with the exception of first gear and reverse gear which should only be selected when stationary and use a ‘Single-Clutch’ action to select other gears.
B1.3 What is a gear ‘splitter’ function?
The Splitter function fitted to many transmissions allows the driver to select an alternative ratio in each gear.
The benefit is that when heavily loaded or when climbing hills, vehicle may not allow a full gear to be changed. By splitting the gear, the vehicle can increase momentum gradually. Sometimes referred to as half gears and be switched to pre-selected, but will only engage the desired ratio when the clutch is depressed.
B1.4 How does an Electronic Control Unit (ECU) affect gear changes?
ECU will ensure that the correct ratio is selected at any time during the journey.
B1.5 What is an automated manual transmission?
An Automated Manual Transmission is a manual transmission where the process of gear selection is automated.
AMT is not ‘Automatic Transmission’ and is only the changing of gear ratios that is automated via the ECU.
B1.6 What type of gearbox ratio would be fitted to a truck?
95% of all new heavy vehicles sold with AMT (Automated Manual Transmission).
B1.7 What type of gearbox ratio to be fitted to a bus or coach?
City buses would be fitted with automatic transmission and coaches would have AMT for long distance.
B1.8 What are the advantages of an automatic gearbox?
Another benefit of the torque converter is it’s ability to absorb large amounts of stress by acting as a damper or impact absorber for the driveline which makes the fully automatic transmission well suited to heavy haulage applications.
B1.9 What are known as two-pedal systems?
AMTs and ATs (ie no clutch pedal)
B1.10 How did electronic gear selection affect the traditional gear linkage assembly?
Made them obsolete.
