
Four speed gearbox construction
Manual gearbox is a type of transmission used in motor vehicle applications. This is article about four speed gearbox construction. We will know about how a four speed gearbox works and its construction.
At the beginning we should know the scheme gearbox working of the gearbox and then we can new information about 4-, 5- speed gearbox construction too.

Four-speed Gearbox Construction: 1 – oil drain plug; 2 – gear housing; 3 – drive shaft; 4 – drive shaft bearing cap; 5, 8, 18 – locking rings; 6 – reverse drive shaft bearing; 7 – roller bearing; 9 – synchronizer coupling of third and fourth gears; 10 – synchronizer coupling of the third and fourth gears; 11 – gear wheel of the third speed; 12 – gear wheel of the second speed; 13 – synchronizer coupling of the first and the second gears; 14 – washer; 15 – synchronizer hub of the first and the second gears; 16 – gear wheel of the first gear; 17 – adjusting washer; 19 – ball bearing; 20 – top cap gearbox; 21 – gearbox extension; 22 – driven shaft; 23 – steel-babbit bearing; 24 – screw cap; 25 – stuffing box; 26 – extension flange; 27 – rubber coupling; 28 – axis of intermediate gear wheel of reverse; 29 – intermediate gear wheel of reverse gear; 30 – gear wheels block of intermediate shaft; 31 – needle bearing of intermediate shaft; 32 – gear wheel reverse gear; 33 – axis of intermediate shaft.
The driving shaft 3 of the four-speed gearbox has a gear wheel permanent gearing connect to the block of gear wheels 30 of intermediate shaft. Other gear wheels of this block are in permanent gearing to the gear wheels 11, 12, 16 according with third, fourth, fifth gears of the driven shaft 22. To turn on all four gears of front moving are used connecting of the sliding couplings 9 and 13 of synchronizers.
How a four-speed gearbox works
When the first speed is on: The crankshaft rotation moment is transmitting to the gear wheels block of intermediate shaft 30 through drive shaft 3, and then to the driven shaft 22 through gear wheel 16, sliding coupling 13 and synchronizer 15 hub of the first and second gears.
When the second speed is on: The crankshaft rotation moment is transmitting to the driven shaft though the drive shaft 3, gear wheels block of intermediate shaft, gear wheel 12, sliding coupling 13 and synchronizer 15 hub of the first and second gears.
When the third speed is on: The crankshaft rotation moment is transmitting to the driven shaft though the gear wheel 11, sliding coupling 9 and synchronizer 10 hub of the third and fourth gears.
When the fourth speed is on: the synchronizer of the third and fourth speed connects drive shaft to the driven shaft directly.
When the reverse gear is on: gear wheel 29 is gearing to gear wheel 32 of the intermediate gear wheels block and gear rim of the synchronizer sliding coupling of the first and second gears.
Also you can learn all about five speed gearbox construction.