What are the differences between the Mercedes-Benz GLE and ML?

What is the function of an automobile piston?

Piston function: The piston's role is to withstand gas pressure and transmit it through the piston pin to the connecting rod, which drives the crankshaft to rotate. The top of the piston also forms part of the combustion chamber. Working principle of the piston: Operating conditions: Pistons operate under conditions of high temperature, high pressure, high speed, and poor lubrication. They are in direct contact with high-temperature gases, with instantaneous temperatures reaching above 2500K. Consequently, they are subjected to severe heating, yet have poor heat dissipation conditions, leading to very high operating temperatures—up to 600-700K at the top—with highly uneven temperature distribution. The piston top endures significant gas pressure, especially during the power stroke, where gasoline engines can reach 3-5MPa and diesel engines 6-9MPa. This results in piston impact and the bearing of lateral forces. Pistons move back and forth in the cylinder at high speeds (8-12m/s), with constantly changing velocities, generating substantial inertial forces and imposing significant additional loads on the piston. Under these harsh conditions, pistons can deform, experience accelerated wear, and develop additional loads and thermal stresses, all while being subjected to chemical corrosion from combustion gases. Piston structure: Generally, pistons are cylindrical in shape. Depending on the engine's operating conditions and requirements, their construction varies. Typically, pistons are divided into three parts: the head, the skirt, and the piston pin boss. Head: The head refers to the top of the piston and the ring groove section. The piston top is entirely determined by the combustion chamber's requirements. A flat or nearly flat top design helps reduce the piston's contact area with high-temperature gases, ensuring uniform stress distribution. Piston skirt: The piston skirt is the lower part of the piston, whose role is to maintain as vertical a posture as possible during reciprocating motion, serving as the guiding part of the piston. Piston pin boss: The piston pin boss is the supporting part where the piston connects to the connecting rod via the piston pin, located above the piston skirt. In high-speed engines, the piston pin boss may not align with the piston's central axis plane but can be slightly offset to one side—specifically, toward the side that contacts the cylinder wall during the power stroke. This offset reduces piston slap against the cylinder wall when the piston changes direction at top dead center, thereby decreasing engine noise.

12

1

Share

Can I Wear Color Blind Glasses for Driver's License Physical Examination?

You can wear color blind glasses for the driver's license physical examination, but whether you can pass the examination depends on the results of the relevant tests. If wearing a pair of color blind glasses allows you to accurately recognize the color blindness test cards, the examiner will determine whether you pass. However, if you still cannot accurately identify the color blindness test cards while wearing color blind glasses, you will not pass the physical examination and will not be able to obtain a driver's license. According to Article 11 of the "Regulations on the Application and Use of Motor Vehicle Driver's Licenses," the physical examination items for learning to drive include: 1. Height: Applicants for large buses, tractors, city buses, large trucks, or trolleybuses must be at least 155 cm tall. Applicants for medium-sized buses must be at least 150 cm tall. This is the first step in the physical examination for learning to drive. 2. Vision: Applicants for large buses, tractors, city buses, medium-sized buses, large trucks, trolleybuses, or trams must have naked or corrected visual acuity of at least 5.0 on the logarithmic visual acuity chart. Applicants for other types of vehicles must have naked or corrected visual acuity of at least 4.9 on the logarithmic visual acuity chart. 3. Color Vision: No red-green color blindness. This is consistent with the vision requirements in the physical examination for learning to drive. 4. Hearing: Able to distinguish the direction of sound sources with each ear at a distance of 50 cm from a tuning fork. 5. Upper Limbs: Both thumbs must be intact, and each hand must have at least three other fingers intact, with normal limb and finger movement functions. 6. Lower Limbs: Normal movement function. Applicants for manual transmission vehicles must have lower limbs no longer than 5 cm. Applicants for automatic transmission vehicles must have a sound right lower limb. 7. Trunk and Neck: No movement dysfunction.

16

1

Share

Why is the low pressure of car air conditioning too high?

There may be several reasons for the high low pressure in car air conditioning: 1. Low pressure drop: If the high pressure rises after adding some oil and the low pressure drops, it may be due to a blocked expansion valve. This could be caused by a failed dryer (receiver-drier), with dirt or possibly metal particles from compressor wear entering the expansion valve and causing blockage. It is recommended to replace the expansion valve and dryer, and perform a no-disassembly cleaning of the air conditioning system pipeline. A failed temperature sensing switch may keep the valve in a normally closed state. Replace the expansion valve and dryer. 2. Low pressure rise: If the high pressure rises slightly after adding oil and the low pressure also rises, there may be air in the pipeline or poor sealing allowing air to enter. The system should be rechecked for leaks, evacuated, and refilled with refrigerant. Blockage in the pipeline system, a blocked or faulty expansion valve should be addressed by replacing the expansion valve and cleaning the pipeline. Another typical symptom is heavy condensation or frost (ice) on the low-pressure pipe. Replace the expansion valve.

4

3

Share

What are the time-based training rules for the driving test?

The time-based training rules for the driving test refer to the requirement of completing a specified number of training hours before being eligible to schedule the test. Taking the C1 license as an example, a total of 62 training hours are required. Specifically, 12 hours must be completed for Subject 1, 16 hours for Subject 2, 24 hours for Subject 3, and 10 hours for Subject 4. No more than 4 training hours can be completed in a single day, and test scheduling is only allowed after the required hours are fulfilled. Pros and cons of the time-based training system: 1. Pros: After implementing the time-based training system, all driving schools will uniformly 'count training hours' and standardize the 'hourly' price. This means the cost will be the same regardless of which driving school you choose. Competition among driving schools will no longer be based on price wars but on service quality and driving skill training. 2. Cons: According to previous regulations, students with good driving aptitude could obtain their license in about 40 days after registration. However, under the new rules, completing 62 training hours is mandatory, and under normal progress, it will take at least 3 months to obtain the license.

11

4

Share

What's the reason for not detecting the key?

There may be two possible reasons why the car cannot detect the key: 1. The key battery is dead: When you press any button on the key, check if the indicator light turns on. If not, the battery needs to be replaced. 2. Poor battery contact: You can remove the key shell, rotate the coin battery, or take it out and reinstall it after a while. Additional information: Precautions for battery replacement: 1. Do not touch the circuit board or battery terminals. 2. The remote control is waterproof. If it gets wet accidentally, dry it immediately. 3. When replacing the battery, ensure there is no dirt, grease, or other foreign matter on the electrode contacts. 4. After replacing the battery, check to ensure all functions of the smart key are working properly.

18

3

Share

How to Steer the Wheel When Turning a Car?

Methods for steering the wheel when turning a car: 1. When making a right turn, do not rotate the steering wheel with your hands but move it. Failing to turn the wheel sufficiently for a right turn can result in incomplete turning, especially at smaller intersections where a larger steering angle is required. Insufficient steering may lead to driving in the wrong direction. Always keep both hands on the wheel. 2. When making a U-turn, turn the steering wheel with your right hand to the 10 o'clock position, using the left hand to receive and the right hand to guide, and vice versa for a left turn. 3. For a right turn, turning the steering wheel one full rotation (360 degrees) is sufficient. It's important to get accustomed to minimal steering adjustments, controlling the wheel within a 5 to 10-degree angle. When taking wide turns, reduce speed and avoid rapid steering to prevent skidding.

7

2

Share

What are the differences between the Mercedes-Benz GLE and ML?

What is the function of an automobile piston?

Can I Wear Color Blind Glasses for Driver's License Physical Examination?

Why is the low pressure of car air conditioning too high?

What are the time-based training rules for the driving test?

What's the reason for not detecting the key?

How to Steer the Wheel When Turning a Car?

What are the pros and cons of buying a car in another location and registering it locally?

What to Do If You Didn't Click Save After Confirming the Electronic Signature for the Driving Test?

What are the replacement criteria for front brake disc wear?

Is the Subject 1 Test the Same in Every Province?