Electric vehicle transmission

Types of Electric Vehicle Transmissions

Electric vehicles (EVs) use electric power instead of traditional internal combustion engines (ICEs). The electric vehicle transmission has different types when compared to ICE vehicles. The EV transmission gives the driver smooth and seamless power delivery, higher efficiency, and a better driving experience. Here are some common types of electric vehicle transmissions:

• Single-speed transmission

  Single-speed transmissions are the most common type of electric vehicle transmission. The transmission consists of a single gear ratio between the electric motor and the wheels. The gear ratio allows the EV to accelerate quickly and reach a high top speed without any difficulty. The single-speed transmission gives the driver a smooth and seamless driving experience. Most EVs with single-speed transmissions have a very linear power delivery. For this reason, drivers don't feel the gear shifting as they accelerate.

• Multi-speed transmission

  Multi-speed transmissions have two or more gears. The transmission allows the driver to select different gear ratios manually or automatically. Multi-speed transmissions enable better control of the vehicle's power delivery. EVs with multi-speed transmissions offer a wider power band and improved efficiency, especially at higher speeds. For this reason, some high-performance EVs and luxury electric vehicles use multi-speed transmissions.

• Two-speed transmission

  Some electric vehicles use a two-speed transmission. The two-speed transmission combines the benefits of single-speed and multi-speed transmissions. It consists of two gears and often comes with a selectable gear ratio (sometimes called a sport mode). The first gear offers high torque for quick acceleration from a standstill. The second gear allows for high-speed cruising on the highway. The two-speed transmission is commonly used in trucks and sports performance electric vehicles.

• Direct drive transmission

  Some manufacturers combine the electric motor and the axle to create a direct drive transmission. The design eliminates the need for a gearbox or complex gear mechanisms. As a result, the driver will enjoy a more responsive, efficient, and low-maintenance drive experience. A direct drive transmission offers a simple and cost-effective solution for many electric vehicles.

• Continuously variable transmission (CVT)

  Continuously variable transmissions (CVT) are not very common in electric vehicles. The CVT allows for an infinite number of gear ratios. This design enables smooth acceleration without any noticeable gear shift. Some luxury EVs and high-performance electric vehicles use the continuously variable transmission to optimize power delivery and efficiency.

Specifications and Maintenance of Electric Vehicle Transmissions

The specifications of any transmission in electric vehicles are essential to understanding its capabilities and attributes. Here are the general specifications of electric vehicle transmissions:

• Gear Ratio

  The gear ratio of the e-axle transmission determines how much torque the driver gets. EVs have a single gear ratio that ranges from 7 to 10. The single gear ratio brings about a smooth driving experience. The gear ratio in multi-speed transmissions differs in every gear.

• Torque Capacity

  The torque capacity of electric vehicle transmission systems determines the amount of torque they can deliver without breaking down. The torque capacity is different for each gear in a multi-speed transmission. However, EVs have a torque capacity of about 400 N·m to 1000 N·m or more.

• Power Output

  The power output in an electric vehicle transmission system determines how much power the system delivers. The power output is also different for each gear in multi-speed transmissions. But the power output for any given gear is between 50 and 150 kW.

• Operating Speed

  The operating speed is the maximum speed the electric vehicle transmission system can reach. This speed depends on the electric motor connected to the transmission. The operating speed of the transmission system is about 20,000 to 25,000 revolutions per minute (RPM).

• Weight

  The weight of the electric vehicle transmission system is crucial during its design and use. Generally, the lighter the transmission system, the better. This is because a lightweight electric vehicle will use less energy and go further. The transmission system's weight is about 60 to 130 kg.

• Cooling System

  The cooling system in an electric vehicle transmission is necessary to keep the transmission at a constant temperature. The cooling system uses electric coolant or water to ensure the transmission does not overheat during use. The cooling system requires a water tank and cooling channels.

Maintaining electric vehicle transmissions is crucial because it helps improve the transmission's performance, extends its lifespan, and reduces repair costs. Here are some maintenance tips for electric vehicle transmissions:

• Regular Inspection: Carrying out a regular inspection helps identify problems early before they escalate. During the inspection, the cables, housing, and linkage of the transmission are checked for wear and damage. Also, the fluid level in the cooling system is checked to see if it is at the required level. Any visible leaks in the cooling system must be looked out for and fixed as soon as possible.
• Fluid Replacement: Replacing the transmission fluid at the recommended intervals is necessary to maintain the electric vehicle transmission. The fluid lubricates the moving parts of the transmission and also helps it shift gears smoothly. During the fluid replacement, the old fluid is drained out and replaced with a new one. The level of the new fluid is checked to ensure it is at the required level.
• Clean the Transmission: Cleaning the electric vehicle transmission helps remove any dirt or debris that could damage it. To clean the transmission, a damp cloth is used to wipe the housing and linkage. The moving parts are also wiped with a lubricant to keep them moving smoothly.
• Professional Maintenance: When there are serious problems with the electric vehicle transmission, it is important to get a professional mechanic to help fix the problem. The mechanic has the right tools and knowledge to work on the transmission safely.

How to Choose Electric Vehicle Transmission

Choosing an electric vehicle transmission can be challenging, considering the many options available. Here are some factors that should be considered when choosing Electric Vehicle transmissions.

• Vehicle Requirements:

  Consider the type of vehicle and its use. Heavier vehicles like trucks need more powerful transmissions to handle their weight, while lighter cars need less. Consider if the vehicle needs fast acceleration, top speed, or a mix of both.

• Gear Ratio:

  Gear ratios determine how power is transferred from the motor to the wheels. A transmission with a higher gear ratio gives better acceleration but lowers top speed. One with a lower gear ratio gives slower acceleration but a higher top speed.

• Size and Weight:

  Avoid heavy transmissions, as they will make the vehicle heavy and reduce its range. Look for lightweight transmissions that are also compact. They should fit well in the vehicle without taking up too much space.

• Efficiency:

  The transmission should have high efficiency to use the most power from the motor. It should have a design that reduces energy loss. An efficient transmission helps the vehicle go farther on a single charge.

• Cost:

  Electric vehicle transmissions can be expensive. Consider the budget and look for transmissions that give good value for the money. Weigh their benefits against their costs. Sometimes, a more costly transmission may save money in the long run through better efficiency.

• Brand Reputation:

  Consider the brand of the transmission. Look for well-known brands with a good reputation for quality. Read reviews from other customers to see what they say about the transmission.

How to DIY and Replace Electric Vehicle Transmission

Here is a simple guide on how to DIY and replace electric vehicle transmissions:

• Safety First:

  Always engage in safety measures before starting any repairs. Ensure the EV's power is turned off, wear insulated gloves, and be mindful of high-voltage components.

• Gather the Necessary Tools:

  To replace an electric vehicle transmission, obtain suitable tools such as wrenches, sockets, torque adapters, screwdrivers, and any specialized EV service tools required for the specific model. Additionally, ensure the new transmission model is compatible with the vehicle.

• Prepare the Vehicle:

  Start by loosening the lug nuts and lifting the EV using a jack. Once the vehicle is elevated, it is possible to remove the wheels and wheel covers. After this, securely hold the car with jack stands and open the hood to access the transmission.

• Disconnect the Transmission:

  Follow the manufacturer's manual to separate the transmission from the EV. Disconnect all the EV transmission cables, hoses, and electrical connections. Be careful with the cooling system and ensure all fluids are adequately drained before disconnection. After this, remove any mounts or supports holding the transmission in place.

• Remove the Old Transmission:

  Once disconnected, use appropriate tools to carefully remove the old transmission from the vehicle. This procedure may require additional assistance because of the transmission's weight and size.

• Install the New Transmission:

  Lift the new transmission into position with the help of a hoist or lifting equipment. Secure it according to the manufacturer's specifications using mounts and support systems. Then, reconnect all cables, hoses, and electrical connections to the transmission. Follow the torque specifications provided in the service manual when tightening bolts and fasteners.

• Finalize the Installation:

  Check all connections, ensure there are no leaks, and verify that the transmission operates correctly. Once the wheel is reattached, lower the vehicle, and perform a final inspection. Before taking a test drive, double-check all systems and settings to ensure everything is in order.

Q and A

Q1: What is the role of gears in electric vehicle transmissions?

A1: Gears in electric vehicle transmissions help control the power and speed of the car. They make it possible to go fast on highways and slow down without trouble. Instead of many complicated gears, some EVs have a simple but effective system that uses one or a few gears to provide a smooth drive.

Q2: How does an electric vehicle transmission differ from a conventional one?

A2: Electric vehicle transmissions are often simpler, with fewer moving parts. They provide direct power from the motors to the wheels, making the drive smoother. This simplicity requires less maintenance and offers better energy efficiency. On the other hand, traditional vehicles rely on multi-gear manual or automatic transmissions, which can be less efficient and require more upkeep.

Q3: What are the advantages of electric vehicle transmissions?

A3: Electric vehicle transmissions have many benefits. They give a smooth and instant power flow to the wheels, making the ride even and comfortable. They often have fewer parts, which means lower maintenance costs. Plus, they are more energy-efficient, helping the car go further on a single charge.

Q4: How do EV transmissions impact vehicle performance?

A4: Transmissions in EVs boost car performance. They ensure the electric motor's power goes straight to the wheels, giving drivers instant acceleration. Whether merging onto highways or overtaking, the car responds quickly. Plus, with fewer parts in the transmission, the ride is smooth, making every trip enjoyable.

Q5: Can the transmission of an electric vehicle be upgraded or modified?

A5: Yes, it is possible to upgrade or modify the transmission of an electric vehicle. Doing this can improve performance, increase torque, or enhance efficiency. However, any changes should be carefully planned and executed to ensure compatibility with the EV's powertrain and electrical systems.