Very Large Trucks

North American manufactured highway trucks often use an engine built by a third party, such as CAT, Cummins, or Detroit Diesel, but both Mack and Navistar offer their own engines.
In the European Union, all new lorry engines must comply with Euro 5 emission regulations.
• Drivetrain
Small trucks use the same type of transmissions as almost all cars, having either an automatic transmission or a manual transmission with synchromesh (synchronizers). Bigger trucks often use manual transmissions without synchronizers, saving bulk and weight, although synchromesh transmissions are used in larger trucks as well. Transmissions without synchronizers, known as "crash boxes", require double-clutching for each shift, (which can lead to repetitive motion injuries), or a technique known colloquially as "floating", a method of changing gears which doesn't use the clutch, except for starts and stops, due to the physical effort of double clutching, especially with non power assisted clutches, faster shifts, and less clutch wear.