Trucks
Volvo I-Shift with crawler gears
The I–Shift with crawler gears is a gearbox designed to provide power and extreme startability, which are crucial to heavy duty assignments.
The gear is so powerful that the truck can start from standstill on a level road with loads of up to 325 tonnes. The gear ratio helps truck operators to drive at speeds as low as 0.5 km an hour – allowing the truck to really move at a crawl. This is a huge help when performing precision manoeuvres, especially when reversing.
The large gear ratio in the I-Shift with crawler gears is achieved by a new gear reduction set that has been added to a standard I-Shift. To make room for the extra gear reduction set, the gearbox is 12 cm longer than a standard I-Shift. Many of the new components, such as gearwheels, engaging sleeves and split synchronisers are made of high-strength materials, which makes the gearbox extremely durable.
CRAWLER GEAR 1: The gear ratio in the lowest gear is 32:1.
The fact that the Volvo Truck’s I–Shift with crawler gears provides so much power and allows for very slow movement makes it ideal for assignments such as timber haulage, operating dump trucks and heavy vehicle combinations. Optimal fuel consumption is achieved both with and without loads.
The gearbox also allows trucks to achieve extreme startability with heavy loads. The unique combination of crawler gears and the optimised rear-axle ratio saves fuel and adds productivity in long-distance transport applications. Another benefit is that the clutch energy of the I-Shift with crawler gears is around 25 per cent compared with a normal I-Shift, greatly reducing wear on the driveline.
CRAWLER GEAR 2: The gear ratio is 19:1. In Volvo Trucks’ manual gearbox with crawler gears it is 17:1.
HOW IT WORKS: I-SHIFT WITH CRAWLER GEAR
The large gear ratio in the I-Shift with crawler gears is made possible by a new gear train that has been added to a standard I-Shift. The I-Shift with crawler gears delivers unique power, startability and manoeuvrability. It also reduces wear on the driveline. So how does it work?
EXTRA GEAR TRAIN
The extra gear train is located directly behind the gearbox coupling and consists of two extra gearwheels – one on the input shaft and one on the intermediate shaft. The extra gear train enables the gearbox to provide a ratio that is almost twice as large as a standard I-Shift.
REVERSE GEAR: Has a gear ratio as low as 37:1, which allows the truck to move at a very low speed. It delivers extreme manoeuvrability, even with heavy loads.
LOW GEAR RATIO
Gear ratio is the difference in speed between the input and output shafts in a gearbox. With the highest gear engaged, the gear ratio is 1:1, which means that the shafts spin at the same speed. At the lowest gear in the I-Shift with crawler gears, the output shaft spins 32 times more slowly than the engine speed.
