Engineering the Future: CVT Transmission Systems and the Critical Role of Lubricants

Transmission systems are crucial for transferring power from the engine to the wheels in vehicles or transmitting signals in communication systems. Here are the main types of transmission systems:

Automotive Transmission Systems:

These systems control the power delivered to the wheels and come in several types:

A. Manual Transmission (MT)

• Driver manually shifts gears using a clutch.
• Offers better control and fuel efficiency.
• Common in Sports cars, budget vehicles, and performance-oriented models.

B. Automatic Transmission (AT)

• Shifts gears automatically without driver input.
• Uses a torque converter instead of a clutch.
• Smoother but less fuel-efficient than manual.
• Common in Most modern passenger cars, SUVs, and luxury vehicles.

C. Continuously Variable Transmission (CVT)

• Uses belts and pulleys for infinite gear ratios.
• Provides smooth acceleration but can feel less engaging.
• Common in fuel-efficient cars (e.g., Toyota Corolla, Honda Civic).

D. Dual-Clutch Transmission (DCT)

• Uses two clutches for quick gear shifts.
• Found in high-performance and some economy cars.
• Faster shifts than traditional automatics.
• Common in Performance cars (e.g., Volkswagen DSG, Porsche PDK)

E. Automated Manual Transmission (AMT)

• Manual transmission with automated clutch and shifting.
• Cheaper than full automatics but can be jerky.
• Common in Budget cars (e.g., Maruti Suzuki AGS, Tata AMT).

Understanding Transmission Fluid Classifications

Transmission fluid is the lifeblood of any transmission system whether manual, automatic, CVT, or dual-clutch. It not only lubricates moving parts but also functions as a coolant, hydraulic fluid, and a means to transfer power smoothly. Using the correct type of transmission fluid is critical to ensure performance, protect components, and maintain long-term reliability

Primary Functions of Transmission Fluids

• Lubricate gears and bearings
• Act as a hydraulic medium for gear shifts
• Cool the transmission by dissipating heat
• Provide frictional properties for clutch engagement
• Prevent corrosion, wear, and sludge formation

Transmission Fluid Common Standards

• TASA Suffix-A
• TASA: Transmission and Steering Axle Specification.
• Suffix-A: An older classification developed by the U.S. military (TASA Suffix-A = MIL specification).
• Was once a common reference for early ATF formulations.
• Now largely obsolete, but still sometimes referenced in older vehicle manuals or third-world applications.
• DEXRON (e.g., DEX II, DEX III & DEX VI)

DEXRON is a GM (General Motors) trademark for its ATF specifications.

• DEXRON-II:

DEXRON-II was General Motors’ second-generation automatic transmission fluid, introduced in the early 1970s. It marked a significant improvement over the original DEXRON (Type-B) fluid, incorporating better performance characteristics to meet the demands of evolving automatic transmission designs. DEXRON-II remained in widespread use through the 1980s and was foundational in the evolution of modern ATF technologies.

• DEXRON-III (DEX III):

DEXRON-III is a specification of automatic transmission fluid (ATF) developed by General Motors (GM). It was introduced in the early 1990s as an evolution of earlier DEXRON fluids, designed to meet the needs of a broad range of GM and non-GM automatic transmissions. Over the years, several versions of DEXRON-III were released, such as DEXRON-III(F), (G), and (H), with incremental improvements in fluid performance and durability.

• DEXRON-VI (DEX VI):

DEXRON-VI is a high-performance, fully synthetic automatic transmission fluid (ATF) developed by General Motors (GM). Introduced in 2005 for the 2006 model year, DEXRON-VI was designed to replace its predecessor, DEXRON-III, offering enhanced performance, durability, and fuel efficiency in automatic transmissions.

•    MERCON (Ford Equivalent)

1. MERCON is Ford’s equivalent to DEXRON.
2. Ford vehicles often specify MERCON, MERCON V, or MERCON LV.

In India, ATF (Automatic Transmission Fluid) is used in vehicles equipped with automatic transmissions, including cars, SUVs, and some commercial vehicles. Here’s a breakdown of where and how ATF is used and relevant in the Indian context:

• Vehicles That Use ATF in India

 Passenger Cars and SUVs

• Increasing number of cars in India now come with automatic gearboxes:
  • AMT (Automated Manual Transmission): Sometimes uses gear oil, but higher-end AMTs may use ATF.
  • Traditional Automatic (Torque Converter AT): Uses ATF (e.g., DEXRON-III, MERCON).
  • CVT (Continuously Variable Transmission): Uses CVT-specific fluid (not regular ATF).
  • DCT (Dual-Clutch Transmission): Uses DCT fluid (some may resemble ATF but are not interchangeable).

 Commercial Vehicles

• Buses and trucks with automatic gearboxes (like some Volvo, Tata, or Ashok Leyland models) use ATF.
• Power steering systems in older vehicles also sometimes use ATF (like DEX II/III).

  Two-Wheelers

• Very few two-wheelers in India use ATF, except for scooters with CVT, which use CVT oil (not ATF).

Continuous Variable Transmissions (CVTs) have become increasingly popular in modern vehicles for their ability to deliver superior fuel efficiency, smooth acceleration, and optimal engine performance. Unlike traditional manual or automatic transmissions, CVTs operate using a belt or chain system between variable-diameter pulleys, which presents unique and demanding lubrication requirements.

How CVT Systems Work & Why Lubrication Is Critical

Continuously Variable Transmissions (CVTs) function quite differently from traditional gear-based systems. Instead of shifting between fixed gear ratios, a CVT uses a combination of components that adjust seamlessly to deliver the most efficient power output at any speed.

Key components of a CVT include:

• Variable-Diameter Pulleys (Sheaves): These adjust automatically to change gear ratios without distinct steps.
• Steel Belt or Chain: Transfers power between the pulleys while operating under high tension and pressure.
• Hydraulic System: Manages pulley movement and clamping force to ensure smooth power delivery.

Because the belt or chain is constantly adjusting and slipping under load, lubrication becomes a critical factor in system health and performance. The transmission fluid must:

• Minimize friction to enable smooth operation while avoiding excessive slip
• Resist shear forces, maintaining its viscosity and performance under constant pressure
• Dissipate heat generated by ongoing friction
• Protect internal components, including gears, bearings, and pulley surfaces, from wear and corrosion

Using an incorrect or substandard CVT fluid can quickly lead to problems like increased wear, overheating, and even transmission failure. That’s why selecting the right fluid isn’t just recommended, it’s essential for ensuring longevity and reliability.

Primary Functions of CVT Lubrication

CVT fluids, commonly referred to as CVTFs (Continuously Variable Transmission Fluids), are engineered to do much more than just lubricate moving parts. They play a vital role in the overall operation and durability of the transmission. Below are the key functions that make CVTFs essential for CVT performance:

1. Friction Control
   The fluid must precisely manage friction between the metal belt or chain and the pulleys. It needs to prevent slippage while allowing smooth, controlled movement to ensure efficient torque transfer.
2. Wear Protection
   With constant metal-to-metal contact in high-pressure zones, CVTFs must provide strong anti-wear protection to reduce component fatigue and extend system life.
3. Thermal Stability
   CVTs often operate under high loads, generating substantial heat. The fluid must resist thermal breakdown and maintain its integrity even at elevated temperatures.
4. Oxidation Resistance
   To maintain cleanliness and prevent internal damage, the fluid must resist oxidation, which can lead to the formation of harmful acids, sludge, and varnish.
5. Shear Stability
   Under intense mechanical stress, the fluid’s viscosity can degrade. CVTFs must maintain their viscosity over time to ensure continued performance throughout the service interval.
6. Foam and Air Release Properties
   Air entrainment or foaming can disrupt hydraulic pressure and reduce lubrication effectiveness. CVT fluids must rapidly release trapped air and prevent foam formation.
7. Hydraulic Functionality
   In many CVT designs, the fluid also acts as a hydraulic medium, controlling pulley pressure, valve actuation, and system response. This requires stable flow characteristics and consistent pressure behaviour.

What Makes CVT Systems Unique?

Continuously Variable Transmissions (CVTs) differ from conventional manual or automatic transmissions in a fundamental way: they don’t rely on fixed gear ratios. Instead, a CVT uses a belt or chain that runs between two variable-diameter pulleys, allowing the transmission to seamlessly adjust to an infinite number of effective gear ratios.

This ability to continuously adapt ensures optimal engine performance and fuel efficiency, but it also introduces unique engineering and lubrication challenges. The belt or chain is constantly in motion, requiring precise control, consistent friction, and high clamping forces to transfer power effectively.

Because of this dynamic operation, CVT systems place extreme demands on the transmission fluid. The lubricant must maintain the perfect balance: providing enough friction to prevent slippage, while also reducing wear and managing heat. Only fluids formulated specifically for CVTs can deliver the performance, protection, and stability needed to support this complex and finely tuned mechanism.

Types of CVT Fluids

Type	Description	Examples
OEM-Specific CVT Fluid	Formulated for a specific manufacturer’s requirements.	Nissan NS-3, Subaru CVT Fluid, Honda HCF-2
Universal CVT Fluid	Meets multiple OEM specs (aftermarket option).	Idemitsu CVT Fluid, Valvoline CVT Fluid
Incorrect or Incompatible Fluids	ATF or manual transmission fluid-can cause damage.	Dexron VI, Mercon LV (Not for CVTs!)

In new scooters, especially the popular automatic scooters in India (like Honda Activa, TVS Jupiter, Suzuki Access, etc.), the CVT (Continuously Variable Transmission) system plays a critical role in how the scooter operates.

Role of CVT in New Scooters

• CVT enables smooth acceleration without manual gear shifting.
• It uses a system of pulleys and a belt to continuously vary the gear ratio.
• Automatically adjusts for speed and load, giving a seamless ride experience.
• Great for city traffic, hence highly popular in India.

People often prefer CVT (Continuously Variable Transmission) over DCT (Dual-Clutch Transmission) for practical, comfort-oriented, and cost-related reasons, especially in everyday driving.

1. Smoother Driving Experience

• CVTs have no actual gear shifts, so the ride is seamless and jerk-free.
• Ideal for city traffic and stop-and-go conditions.
• Especially appreciated by elderly drivers, commuters, or those prioritizing comfort.

2. Better Fuel Efficiency in City Driving

• CVTs keep the engine at its optimal RPM for efficiency.
• Especially good in low-speed urban conditions, where DCTs might hunt for gears.

3. Lower Maintenance (In Some Cases)

• Fewer moving parts than DCTs.
• No clutch packs to wear out like in DCT.
• Service intervals can be longer (though CVT belts eventually wear out too).

4. Cost-Effective

• CVTs are cheaper to manufacture and usually cost less upfront.
• Found in many affordable vehicles like:
• Honda Amaze CVT
• Maruti Baleno CVT (older gen)
• Toyota Hyryder (e-CVT)
• Scooters like Honda Activa, TVS Jupiter

5. Reliable for Light to Moderate Loads

• CVTs perform well in vehicles with modest power output.
• Smooth and reliable in daily commuter cars and scooters.

Benefits of CVT (Continuously Variable Transmission) Over Traditional Transmission Systems:

A Continuously Variable Transmission (CVT) is an automatic transmission that uses a system of pulleys and a flexible belt or chain to provide an infinite range of gear ratios. Unlike traditional transmissions, which rely on a fixed set of gears, a CVT adjusts seamlessly to match the engine’s power output with the vehicle’s speed, offering several advantages.

1. Smoother Driving Experience

• Seamless Acceleration:
  CVTs eliminate the noticeable shift points in traditional automatic transmissions, providing smooth and uninterrupted acceleration.
• No Gear Hunting:
  Traditional automatics may “hunt” between gears under certain driving conditions. CVTs continuously adapt, avoiding this behaviour.

 2. Improved Fuel Efficiency

• Optimal Engine RPM:
  CVTs keep the engine operating at its most efficient RPM, especially during cruising, reducing fuel consumption.
• Lighter Weight:
  Generally, CVTs are lighter than traditional transmissions, contributing to better overall vehicle efficiency.

3. Better Performance in Certain Conditions

• Hill Climbing:
  CVTs can maintain a steady engine speed during uphill climbs, improving power delivery and efficiency.
• Urban Driving:
  The ability to maintain optimal power at low speeds makes CVTs especially effective in stop-and-go traffic.

4. Simpler Mechanical Design

• Fewer Moving Parts:
  Compared to multi-gear transmissions, CVTs have fewer components, which can mean lower manufacturing costs and potentially fewer mechanical failures.

5. Enhanced Engine Control

• More Precise Control:
  CVTs allow automakers to fine-tune how the engine responds to throttle input, improving drivability and sometimes offering a more refined driving feel.

6. Adaptive to Driving Conditions

• Dynamic Adjustment:
  Whether climbing a hill, towing, or coasting on a highway, a CVT can instantly adjust its gear ratio for optimal performance without any delay.

Benefits of CVT in 4-Wheelers (Cars, SUVs, Crossovers):

Smoother Driving Experience

• Eliminates gear shifts, resulting in seamless acceleration without shift shock.
• Ideal for urban driving and traffic congestion.
• Improved Fuel Efficiency
• Keeps the engine running at the most fuel-efficient RPM, especially during cruising.
• Helps meet stricter emission and fuel economy standards.

Better Low-Speed Control

• Offers precise control during stop-and-go traffic or hill starts, improving comfort and drivability.

Compact and Lightweight

• CVTs are typically lighter and more compact than traditional automatics, reducing overall vehicle weight.

Cost-Effective Production

• Simpler mechanical design can lead to lower manufacturing costs, benefiting entry-level and economy vehicles.

Benefits of CVT in 2-Wheelers (Scooters, Motorcycles):

• Ease of Use – “Twist and Go” Convenience

No clutch or gear shifting makes riding extremely simple, especially useful for beginners and city riders.

• Better Fuel Economy

Like in cars, CVTs in scooters/motorcycles keep the engine at optimal RPM, leading to better mileage.

• Reduced Rider Fatigue

Riders don’t need to worry about clutch control or frequent shifting in traffic, great for urban commuting.

• Smooth Acceleration

Instant, jerk-free response from standstill to cruising speed enhances comfort.

• Lower Maintenance

Fewer moving parts (especially in belt-driven CVTs), leading to less frequent maintenance and ease of repair.

Whether it’s the smooth driving of a car or the convenience of a scooter, CVT systems enhance performance, fuel efficiency, and user-friendliness in both 4-wheelers and 2-wheelers. As mobility trends shift toward urbanization and fuel economy, CVT remains a smart transmission choice for everyday drivers and riders.

Continuously Variable Transmissions (CVTs) offer a modern solution for enhancing vehicle efficiency and driving comfort. While they may not be ideal for high-performance applications or drivers seeking a more engaged driving experience, CVTs excel in daily commuting, urban environments, and maximizing fuel economy. Advances in CVT technology are steadily addressing past concerns related to noise, reliability, and towing capacity.

Due to the constant mechanical engagement between belts or chains and variable-diameter pulleys, CVTs place unique and demanding requirements on lubrication systems. These transmissions rely on specially formulated CVT fluids that provide exceptional shear stability, precise friction control, and high thermal resistance. Using the correct fluid and following manufacturer-recommended maintenance intervals is critical to ensuring long-term performance, preventing premature wear, and avoiding overheating or potential transmission failure.

For expert advice and high-quality products, don’t hesitate to visit Palco’s Official Website (http://www.palco.co.in) or contact directly at the Email: enquiry@palco.co.in & Phone: +91 93117 94519.