Lack of oil in the steering vertical shaft: heavy steering caused by this fault is very common. Generally, it is because the oil passage is blocked by low-quality grease, so that the butter can not be injected, resulting in dry grinding or even seizure of the vertical shaft. In this case, the pressure bearing will also be damaged quickly.
It is essential to select good oil products to maintain the steering system within the specified time. Poor oil products seem cheap, but they are easy to cause some faults, and maintenance will cost more resources. The same is true for other truck systems. Blindly pursuing low prices in maintenance will often bring greater costs.