Last week, we talked about the difference between a differential and a differential lock. The differential is an important device to ensure that the vehicle turns normally, and the differential lock is an off-road equipment that exists to allow the vehicle to get out of trouble. The function of the differential lock is to lock the differential so that the wheels on both sides get the same power. When one wheel slips, the differential lock can allow the power to be completely transmitted to the side wheel with grip, thereby helping the vehicle to get out of trouble. Therefore, the differential lock has become one of the important criteria for measuring the off-road capability of a hardcore SUV.
At present, hardcore SUVs and off-road vehicles generally adopt the following three differential lock structures:
The first type: Jaw-type differential lock
Representative models: SAIC MAXUS D90 Pro, Nissan Tuda, Jeep Wrangler.
For the differential lock for hard connection, the jaw type is the real hard connection. Its working principle is to make the jaw type pressure plate installed on the two half shafts bite each other under the action of the pressure plate drive mechanism, so that the differential loses the differential function.
When the wheels on both sides are not slipping, the power is 50:50; when one wheel is slipping, the other wheel can get all the driving force, so that the vehicle can get out of trouble.
It is worth noting that the same is the jaw-type differential lock, and the pressure plate drive mechanism has its own advantages. Some rely on electromagnetic to generate suction drive, and some rely on external air pressure. Why not unify the best solution? Because they have their own advantages and disadvantages, the electric suction lock can not be affected by the weather, but the disadvantage is that the bite force is not large; the pneumatic lock has a large bite force, but the performance is unstable due to the weather, because it is an external pipeline, which is easy to leak; the vacuum lock has The advantages of the first two, but the vacuum will decrease after the engine speed increases, and the bite force will decrease.
Regardless of the drive type of the jaw differential lock, the pre-lock function can be realized. In the off-road conditions where the speed is not fast, the driver has enough time to judge whether the road ahead A differential lock is required, which is more efficient than automatically locking after the vehicle starts to slip. It is more obvious that on extremely soft roads, excess slip will cause the vehicle to sink deeper. If the differential is not locked in advance, it will be difficult to drive the vehicle by itself if it is locked and locked.
Jaw-type differential lock has another advantage, that is, the jaw-type hard connection will not encounter the overheating problem of the multi-disc clutch, and it will not make the hardcore SUV look delicate.
The second type: EATON (Eaton) self-locking mechanical differential lock
Representative models: Yusheng S350, Haval H9.
This This type of differential lock was introduced by Eaton, a US company specializing in power system management. The structure is that a locking block is installed on the half shaft inside the differential housing, and the locking block is embedded in the differential housing to form a hard connection when the locking condition is met.
When the Eaton self-locking mechanical differential lock works, it needs to meet simultaneously: 1. The wheel speed is lower than 48km/h; 2. The wheel speed difference is higher than 100 revolutions/min. When the wheel speed exceeds 48km/h or the torque on both sides of the axle is reversed, it will automatically unlock. The advantage of this feature is that no additional operations are required; but because of its rough working method, noise will be generated when locking.
The third type: Electronically controlled limited slip LSD
Representative models: Toyota Prado, Jimny, etc.
LSD is the abbreviation for limited slip differential. It is an improved differential that restricts wheel slip. This differential allows the speed difference of the driving wheels on both sides to be allowed within a certain range to ensure normal turning performance. The LSD can distribute power in a large range through the multi-disc clutch. Some LSDs cannot be completely locked, and some LSDs can be completely locked, but because of the friction structure, the durability is not as strong as the differential lock. However, LSD can fully make up for the shortcomings of traditional differentials and increase the vehicle's cornering speed. Therefore, many high-performance original models will be equipped with LSD devices.
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LSD is not as reliable as the jaw differential lock and Eaton differential lock, it is smart and has a relatively large range of power distribution, which can already meet the general off-road conditions. At present, many mainstream off-road vehicles also use a combination of differential lock and LSD to achieve the passing performance comparable to the three locks, and they are not as easy to damage the front axle as the third lock, such as SAIC MAXUS D90 Pro.
Summary:
There is no absolute good or bad for any kind of differential lock. Both the jaw type mechanical differential lock and the Eaton self-locking differential lock can achieve real hard connection locking. The advantage of the jaw type is that it can be manually pre-locked. When the wheel is locked, the wheel is at a standstill. The noise and impact are very small; the advantage of Eaton's self-locking is that it is fully automatic without human intervention, and the disadvantage is also obvious. Because the wheels are rotating when locked, the noise and impact are relatively strong. The electronically controlled limited slip LSD is more used in light off-road scenes, or used in combination with the first two. If it were you, which differential lock would you choose?
