Universal Joint In A Car: Composition, Classification, and Industrial Applications

Types of Universal Joints in a Car

A universal joint (UJ or U-joint) is a critical mechanical component in a vehicle's drivetrain that allows the transmission of power between two shafts that are not in a straight line. These joints accommodate angular misalignment and are essential for smooth torque delivery, especially in rear-wheel and four-wheel drive vehicles. Auto parts suppliers offer various types of universal joints in bulk to meet the diverse needs of automotive repair shops, OEM manufacturers, and performance tuning specialists.

Cross Type UJ

Also known as the spider and yoke joint, this is the most widely used universal joint in automotive applications. It features a cross-shaped center (spider) with four arms that connect to yokes on the input and output shafts via needle bearings. This design allows angular movement in multiple planes while maintaining robust torque transfer.

Advantages

• High torque capacity and mechanical strength
• Simple, proven design with decades of reliability
• Cost-effective and widely available
• Easily serviceable with standard tools

Limitations

• Velocity fluctuations at high angles
• Requires regular lubrication in non-sealed versions
• Wear over time can cause vibrations or clunking noises

Best for: Drive shafts in trucks, SUVs, and rear-wheel drive vehicles

Single Hooke Type UJ

Named after its inventor Robert Hooke, this joint operates on the principle of angular flexibility in two perpendicular planes. It allows rotational motion between shafts at a fixed angle, making it ideal for applications where alignment is consistent but not perfectly linear.

Advantages

• Effective for moderate angular misalignment
• Compact and lightweight design
• Reliable in low-torque, low-speed environments

Limitations

• Not suitable for high-torque or high-speed applications
• Produces non-uniform output speed (velocity variation)
• Limited angular range before efficiency drops

Best for: Auxiliary drives, agricultural machinery, and light-duty industrial equipment

Double Hooke Type UJ

This configuration uses two Hooke-type joints connected in series, typically at opposite ends of a driveshaft. When properly aligned (with the yokes in phase), the velocity fluctuations from one joint are canceled out by the other, resulting in smoother power delivery and reduced vibration at higher speeds.

Advantages

• Smooth, constant-velocity-like output
• Reduced vibration and noise at high RPMs
• Improved drivetrain balance and longevity
• Ideal for longer drivelines with multiple angles

Limitations

• More complex assembly and alignment required
• Higher cost due to additional components
• Sensitive to improper phasing during installation

Best for: Luxury sedans, performance vehicles, and commercial trucks requiring smooth high-speed operation

Flexible Type UJ

Made from elastomeric materials like rubber or polyurethane, flexible universal joints use a flexible coupling to transmit torque while accommodating misalignment, vibration, and minor angular deviations. These joints are often found in compact or space-constrained drivetrain setups.

Advantages

• Excellent vibration damping and noise reduction
• Compensates for misalignment without wear
• No lubrication required
• Lightweight and corrosion-resistant

Limitations

• Lower torque capacity compared to metal joints
• Can degrade over time due to heat and UV exposure
• Not suitable for high-power or high-temperature environments

Best for: Secondary drives, auxiliary systems, and electric vehicle powertrains where quiet operation is key

Slip Type UJ

A slip-type universal joint incorporates a splined section that allows axial movement (telescoping) in addition to angular flexibility. This feature enables the driveline to change length dynamically, which is essential when suspension movement alters the distance between the transmission and differential.

Advantages

• Accommodates changes in driveline length
• Prevents binding and stress during suspension travel
• Enhances drivetrain durability and safety
• Commonly integrated into modern driveshafts

Limitations

• Requires proper lubrication to prevent spline wear
• Can develop play or looseness over time
• Potential for contamination if seals fail

Best for: Rear-wheel and four-wheel drive vehicles with independent or dynamic suspension systems

Expert Tip: When replacing universal joints, especially in high-performance or heavy-duty applications, ensure proper phasing of double Hooke joints and lubricate slip splines with high-quality molybdenum disulfide grease to extend service life and reduce driveline vibrations.

How to Choose the Right Universal Joint for Your Vehicle

Universal joints (U-joints) are essential components in a vehicle’s drivetrain, enabling smooth power transmission between rotating shafts that are not in a straight line. Auto parts retailers and mechanics should stock a variety of high-quality U-joints to meet the diverse needs of drivers, from everyday commuters to heavy-duty truck operators. Selecting the correct U-joint involves understanding key technical and mechanical factors to ensure durability, performance, and compatibility.

Key Factors When Choosing a Universal Joint

Material Composition

The material used in manufacturing a U-joint directly impacts its strength, wear resistance, and service life. High-carbon steel and advanced alloy steels are widely preferred due to their superior tensile strength and ability to withstand high stress and torsional forces.

These materials are especially beneficial in heavy-duty applications such as commercial trucks, off-road vehicles, and towing equipment. Using high-grade materials ensures reduced deformation under load, better fatigue resistance, and longer intervals between replacements. Always match the U-joint material to the vehicle’s operating conditions—harsh environments may require corrosion-resistant coatings or sealed bearings.

Type of Universal Joint

The most common type is the **cross or Cardan joint**, known for its four-armed cross design that accommodates angular misalignment between connected shafts. It's widely used in automotive driveshafts due to its reliability and cost-effectiveness.

For specialized applications, other types include:

• Double Hooke’s Joint: Reduces speed fluctuations and vibration in high-speed shafts.
• Slip-Type U-Joint: Allows axial movement in addition to angular flexibility, ideal for drivelines with dynamic length changes.
• Flexible U-Joints: Use elastomeric or rubber elements to dampen shocks and reduce noise, suitable for lighter vehicles.

Selecting the right type depends on the vehicle’s drivetrain configuration, operating speed, and load requirements.

Compatibility & Fitment

Universal joints are not one-size-fits-all. Each vehicle model has specific dimensions, including yoke width, bearing cap diameter, and overall length. Even minor mismatches can lead to improper installation, increased vibration, premature wear, or driveline failure.

To ensure proper fitment:

• Measure existing U-joints before replacement.
• Cross-reference part numbers with OEM specifications.
• Verify compatibility with the driveshaft, differential, and transmission output shaft.

Using a compatible U-joint ensures smooth power transfer, minimizes stress on adjacent components, and maintains drivetrain balance.

Load Capacity & Torque Handling

The load capacity of a U-joint defines the maximum torque and force it can transmit without failure. Exceeding this limit can result in joint fracture, driveline vibration, or complete drivetrain breakdown.

Vehicles used for towing, hauling, or off-road driving require U-joints with higher load ratings. When selecting a joint:

• Review the engine’s torque output and transmission characteristics.
• Consider duty cycle—continuous heavy loads demand reinforced joints.
• Upgrade to heavy-duty or greasable U-joints for commercial or performance applications.

Matching the U-joint’s capacity to the vehicle’s powertrain ensures long-term reliability and safety.

Angle of Articulation

This refers to the maximum angular misalignment a U-joint can accommodate while still functioning efficiently. Most standard U-joints operate effectively within 15° to 25°, but performance degrades at higher angles due to increased vibration and non-uniform rotational speed.

In vehicles with significant suspension travel—such as 4x4s, lifted trucks, or off-road rigs—the operating angle can vary dramatically. In such cases:

• Select U-joints rated for higher articulation angles.
• Consider double-cardan or constant velocity (CV) joints for angles exceeding 25°.
• Avoid prolonged operation at extreme angles to prevent accelerated wear.

Proper articulation ensures consistent power delivery and reduces stress on the entire driveline.

Environmental & Operational Conditions

Beyond basic specs, consider where and how the vehicle is used. Exposure to moisture, dirt, road salt, or extreme temperatures affects U-joint longevity.

For harsh environments:

• Choose sealed or greasable U-joints with protective boots.
• Opt for corrosion-resistant finishes like zinc plating or black oxide.
• Ensure regular lubrication access if applicable.

Regular maintenance, such as greasing and inspection, significantly extends service life, especially in demanding applications.

Recommended Maintenance Tips

Important: Installing an incorrect or low-quality U-joint can lead to driveline failure, loss of vehicle control, or costly damage to the transmission or differential. Always use OEM-spec or high-grade aftermarket parts, and follow manufacturer guidelines for installation and torque specifications. Proper selection and maintenance not only extend component life but also enhance vehicle safety and performance.

Commercial Use Cases of Universal Joints in Automotive and Industrial Applications

Universal joints (U-joints) are critical components in drivetrain systems, enabling smooth torque transmission between rotating shafts at variable angles. Their reliability and versatility make them indispensable across multiple commercial sectors. Supplying U-joints in bulk offers significant profit potential for auto parts distributors, wholesalers, and retailers due to consistent demand from repair services, fleet operators, and industrial users. Understanding the diverse commercial applications of U-joints helps businesses tailor inventory, optimize pricing, and deliver value-driven solutions.

Vehicle Repair Shops

Auto repair facilities routinely diagnose and replace worn or damaged U-joints as part of drivetrain maintenance. Since all rear-wheel and four-wheel drive vehicles rely on driveshafts equipped with universal joints, mechanics must identify the correct joint type based on vehicle make, model, year, and drivetrain configuration.

• Technicians perform vibration diagnostics and visual inspections to detect worn bearings, play, or corrosion in U-joints
• Replacement often includes配套 components such as yokes, clips, and grease fittings to ensure long-term performance
• Wholesale purchasing allows shops to maintain an inventory of common U-joint sizes and types, reducing turnaround time for repairs
• Bulk procurement lowers per-unit costs, improving profit margins on labor-intensive drivetrain services

Key Insight: Offering application-specific U-joint kits with installation hardware increases customer satisfaction and reduces return rates.

Aftermarket Auto Parts Retailers

Aftermarket retailers serve a growing market of performance enthusiasts, off-road builders, and DIY mechanics who seek upgrades beyond OEM specifications. Many factory U-joints are designed for standard driving conditions and may fail under high-torque or extreme-angle applications.

• High-performance U-joints made from alloy steel or chrome-moly materials offer greater strength and durability
• Aftermarket options include greasable, maintenance-free, and constant-velocity (CV) hybrid joints for specialized uses
• Retailers stock a wide range of sizes—from compact passenger cars to heavy-duty trucks and SUVs—to meet diverse customer needs
• Bulk buying enables competitive pricing and faster order fulfillment, especially during peak repair seasons

Pro Tip: Bundle U-joints with installation tools or seal kits to increase average transaction value.

Fleet Maintenance Companies

Commercial fleets—including delivery trucks, utility vehicles, and public transit buses—operate under demanding conditions that accelerate wear on drivetrain components. Fleet managers prioritize uptime, consistency, and cost control when managing maintenance operations.

• Preventive maintenance schedules often include routine U-joint inspections and replacements before failure occurs
• Purchasing U-joints in bulk ensures standardized parts across the fleet, simplifying training and repairs
• Wholesale pricing significantly reduces long-term maintenance costs across hundreds or thousands of vehicles
• Having spare joints on hand minimizes downtime and keeps vehicles in service, directly impacting operational efficiency

Strategic Advantage: Offer fleet accounts volume discounts and just-in-time delivery options to build long-term partnerships.

Commercial Car Dealerships

Dealerships—especially those servicing domestic, luxury, or performance brands—require access to both OEM and upgraded U-joint options. While new vehicles rarely need U-joint replacements, service departments handle aging models and customer-specific modifications.

• OEM-certified U-joints are essential for warranty-compliant repairs and brand-specific servicing
• Performance divisions may install heavy-duty joints for off-road packages or towing upgrades
• Bulk purchasing allows dealerships to stock critical drivetrain parts without tying up excessive capital
• Dealers benefit from supplier reliability and fast restocking to maintain high customer service levels

Value-Add Opportunity: Provide technical data sheets and fitment guides to help dealership technicians select the correct joint quickly.

Industrial and Commercial Equipment Applications

Universal joints extend far beyond automotive use—they are vital in industrial machinery, agricultural equipment, mining vehicles, and construction machinery. These applications often involve higher torque loads, dust, moisture, and continuous operation.

• Heavy-duty U-joints with reinforced cross bearings and sealed lubrication systems withstand harsh environments
• Agricultural combines, excavators, and conveyor systems rely on specialized joints for power transmission
• Industrial suppliers purchase in large volumes to support in-house maintenance teams and field service operations
• Custom or oversized U-joints may be required for unique equipment, creating niche markets for specialty suppliers

Growth Area: Partner with industrial distributors to supply ruggedized, corrosion-resistant joints for mining and marine applications.

Benefits of Wholesale U-Joint Distribution

Sourcing and selling universal joints in bulk delivers strategic advantages across all commercial segments. A well-managed inventory of U-joints supports rapid service response, reduces operational costs, and enhances customer loyalty.

• Cost Efficiency: Bulk pricing reduces per-unit cost, increasing profit margins for resellers
• Inventory Reliability: Consistent supply prevents stockouts during high-demand periods
• Application Flexibility: Wide product range supports everything from compact cars to industrial rigs
• After-Sales Support: Offering warranties and technical support builds trust with professional customers
• Scalability: U-joints are compact and easy to store, making them ideal for scalable distribution networks

Smart Strategy: Develop tiered product lines (economy, standard, premium) to serve different market segments effectively.

Professional Recommendation: Focus on building relationships with commercial buyers by offering bulk pricing tiers, technical documentation, and fast shipping options. Emphasize product quality—such as heat-treated cross shafts, precision-machined yokes, and double-sealed bearing caps—as a differentiator over low-cost imports. Providing reliable, durable U-joints reduces return rates and positions your brand as a trusted partner in drivetrain integrity.

Additional Considerations for U-Joint Suppliers

• Quality Standards: Look for U-joints manufactured to ISO or SAE specifications, with materials traceability and load testing data
• Compatibility Tools: Offer online fitment guides or VIN-based lookup systems to simplify part selection
• Warranty Programs: Extended warranties (1–3 years) enhance buyer confidence and reduce perceived risk
• Environmental Resistance: Joints with rubber boots, sealed bearings, and anti-corrosion coatings perform better in wet or dirty conditions
• Brand Recognition: Partner with reputable manufacturers known for durability and technical support

Specifications and Maintenance of Universal Joints in Cars

Understanding the specifications and proper maintenance of universal joints (U-joints) is essential for vehicle owners, mechanics, and automotive enthusiasts. As a critical component of the drivetrain, the U-joint allows for smooth power transfer from the transmission to the differential, accommodating changes in angle and distance. Neglecting U-joint care can lead to costly driveline damage, poor performance, and even dangerous driving conditions. This guide provides comprehensive insights into U-joint specifications, lubrication practices, failure symptoms, and replacement procedures to help ensure reliable and safe vehicle operation.

Safety Warning: Always work on a stable, level surface with the vehicle securely supported by jack stands. Never work under a vehicle supported only by a jack. Disconnect the battery before beginning driveshaft work to prevent accidental engine start-up. Wear protective gloves and eyewear when handling sharp tools or rotating components.

Key U-Joint Specifications to Know

Universal joints are not one-size-fits-all components. Each vehicle model requires a specific U-joint design that matches the original equipment manufacturer (OEM) specifications. Using incorrect parts can lead to misalignment, premature wear, and driveline vibrations. Always consult your vehicle’s service manual or a trusted online parts database to identify the correct U-joint for your make, model, and year.

• Dimensions: Measure critical dimensions such as cross diameter, trunnion length, and overall joint width. Even small discrepancies can affect fitment and performance.
• Series Designation: U-joints are often categorized by series numbers (e.g., 1310, 1330, 1350), which indicate strength, size, and load capacity. Higher series numbers typically denote heavier-duty applications.
• Yoke Configuration: The yoke design—whether it's a slip yoke, fixed yoke, or flanged yoke—must match the driveshaft and differential input shaft.
• Caps and Retainers: Pay attention to the type of retaining mechanism: internal snap rings, external clips, or bolt-in caps, as these affect installation and serviceability.
• Material and Duty Rating: Performance and heavy-duty vehicles may require heat-treated steel or greasable joints designed for high torque and stress.

Never assume compatibility based on appearance alone. Two U-joints may look similar but differ in internal tolerances or load ratings, leading to early failure.

Proper Greasing of U-Joints

Lubrication is one of the most effective ways to extend U-joint life. Regular greasing reduces friction, prevents corrosion, and keeps contaminants like dirt and moisture from entering the joint bearings.

• Use a high-quality, lithium-based or molybdenum-disulfide (moly) grease suitable for high-pressure environments.
• Attach a grease gun with the appropriate nozzle to the zerk fitting on the U-joint cap.
• Apply grease slowly and steadily until fresh grease begins to emerge from the seals or the joint slightly expands—this indicates full lubrication.
• Do not over-grease: Excessive pressure can rupture rubber seals or boot covers, leading to grease loss and contamination.
• Wipe away any excess grease to prevent dirt accumulation and maintain a clean driveline.

Follow your vehicle manufacturer’s recommended lubrication interval—typically every 5,000 to 10,000 miles for serviceable joints. Vehicles used in dusty, wet, or off-road conditions may require more frequent greasing. Sealed U-joints do not have grease fittings and are designed to be maintenance-free, but should still be inspected regularly.

Expert Tip: During routine maintenance, rotate the driveshaft by hand while greasing to ensure even lubricant distribution across all needle bearings inside the joint.

Signs of a Failing U-Joint

Catching U-joint problems early can prevent catastrophic driveline failure. Common symptoms include:

• Clunking or knocking noises: Especially noticeable during acceleration or deceleration, indicating excessive play in the joint.
• Driveline vibrations: Felt through the floorboard or steering column, increasing with vehicle speed. This often means the joint is worn and no longer rotating smoothly.
• Sudden jerking or shuddering: When shifting into drive or reverse, suggesting looseness in the U-joint.
• Visible wear or movement: Inspect the joint for cracked or missing seals, rust trails, or wobbling when the driveshaft is moved by hand.
• Difficulty in power delivery: Power may "jump" or hesitate due to inconsistent torque transfer from a worn joint.

A completely failed U-joint can cause the driveshaft to detach, potentially damaging the undercarriage, fuel lines, or exhaust system. In extreme cases, it can lead to loss of vehicle control. If you notice any of these signs, inspect the U-joint immediately.

U-Joint Replacement Procedure

Replacing a worn U-joint is crucial to prevent further damage to the driveshaft, differential, or transmission. While some vehicles allow in-place replacement, others require complete driveshaft removal.

1. Secure the Vehicle: Park on a level surface, engage the parking brake, and use wheel chocks. Lift the vehicle using a hydraulic jack and support it with jack stands.
2. Mark the Driveshaft: Use paint or a marker to align the driveshaft and differential flange before removal. This preserves proper phasing and balance.
3. Remove the Driveshaft: Disconnect the U-bolts or flange bolts at both the transmission and differential ends. Carefully slide the driveshaft out, supporting its weight to avoid damaging the seal or yoke.
4. Remove Old U-Joints: Use a U-joint press, hammer and punch, or specialized removal tool to push out the trunnions and caps. Remove all retaining clips or snap rings.
5. Install New U-Joints: Insert the new joint into the yoke ears and align the cross. Press in the caps evenly and secure them with new retaining rings or clips.
6. Reinstall the Driveshaft: Slide the shaft back into place, aligning your marks. Reconnect the bolts and torque them to manufacturer specifications.
7. Test the System: Lower the vehicle and start the engine. Check for vibrations, noises, or binding. Perform a short test drive at low speed to verify smooth operation.

Maintenance Reminder: Include U-joint inspection in your regular undercarriage checks—especially after off-road driving or towing. Early detection of wear can save hundreds in repair costs and prevent roadside breakdowns.

Additional Recommendations

• Replace both U-joints on a driveshaft at the same time, even if only one shows wear—this ensures balanced performance and prevents future comebacks.
• Use OEM or high-quality aftermarket U-joints; cheap alternatives may fail prematurely under stress.
• After replacement, recheck the driveshaft balance and operating angles, especially if modifications (like lift kits) have been made.
• Listen for changes in driveline noise after repairs—this helps confirm a successful fix.
• Keep a maintenance log noting grease intervals and replacement dates for future reference.

Proper care of your vehicle’s universal joints ensures smooth power delivery, reduces wear on related components, and enhances overall driving safety. Whether you're maintaining a daily driver or a high-performance rig, understanding U-joint specifications and maintenance practices is a valuable skill. When in doubt, consult a professional driveline technician to ensure the job is done correctly and safely.

Frequently Asked Questions About Universal Joints (U-Joints)

A universal joint, commonly known as a U-joint, is a mechanical component in a vehicle's drivetrain that allows rotational motion to be transferred between two shafts that are not perfectly aligned. This is especially important in rear-wheel-drive and four-wheel-drive vehicles, where the driveshaft connects the transmission to the differential.

The U-joint accommodates angular movement caused by suspension travel and drivetrain flex. As the vehicle moves over uneven terrain, the angle between the transmission and rear axle changes. The U-joint compensates for these variations, allowing smooth power delivery while maintaining mechanical integrity.

In essence, the U-joint acts as a flexible coupling that ensures continuous rotation and torque transfer, even when the connected shafts operate at different angles—keeping the drivetrain synchronized and efficient.

No, while both U-joints and constant velocity (CV) joints allow angular movement in a drivetrain, they differ significantly in design, application, and performance:

• Design: A U-joint uses a cross-shaped yoke with needle bearings in four arms, allowing articulation in two perpendicular planes. In contrast, a CV joint uses a more complex spherical or ball-cage design that maintains constant velocity across a wider range of angles.
• Motion Smoothness: U-joints produce slight speed fluctuations during rotation unless used in pairs (double Cardan configuration), whereas CV joints deliver smooth, consistent rotational speed regardless of angle—making them ideal for front-wheel-drive axles.
• Angle Tolerance: CV joints can operate efficiently at much steeper angles (up to 50°) compared to U-joints (typically limited to 20–25°), which makes CVs better suited for steering axles.
• Applications: U-joints are typically found in older vehicles, trucks, and rear driveshafts. CV joints dominate modern front-wheel-drive and all-wheel-drive vehicles due to their superior performance in dynamic suspension and steering systems.

While both serve similar purposes—transmitting torque through misaligned shafts—they are not interchangeable in most applications. A U-joint is not a CV joint, and vice versa.

U-joint failure can stem from several mechanical and environmental factors. Common causes include:

• Lack of Lubrication: Many U-joints have grease fittings and require periodic lubrication. Without proper greasing, internal needle bearings dry out, leading to metal-on-metal friction and rapid wear.
• Contamination: Dirt, moisture, or road debris can enter the joint if the grease seals are damaged or worn, accelerating corrosion and bearing degradation.
• Excessive Driveshaft Angles: If the suspension is modified or components are worn, abnormal operating angles place uneven stress on the U-joint, causing premature fatigue.
• Wear and Age: Over time, normal use leads to wear in the cross and yoke bearings. Even well-maintained joints eventually degrade after tens of thousands of miles.
• Harsh Driving Conditions: Frequent towing, off-roading, sudden acceleration, or hard braking increases stress on the drivetrain, contributing to early U-joint failure.
• Improper Installation: Incorrect assembly, unbalanced driveshafts, or loose U-bolts can create vibrations and misalignment that shorten joint life.

Symptoms of a failing U-joint include clunking noises when shifting, vibrations under acceleration or deceleration, and visible play in the driveshaft. Early detection can prevent costly damage to the transmission or differential.

For U-joints equipped with grease fittings (zerk fittings), regular lubrication is essential for longevity. The recommended service interval depends on driving conditions and manufacturer specifications:

• Standard Recommendation: Lubricate every 5,000 to 10,000 miles under normal driving conditions.
• Severe Conditions: If you frequently tow, drive off-road, or operate in dusty or wet environments, lubricate every 3,000 to 5,000 miles.
• Preventive Maintenance Tip: Many mechanics suggest greasing U-joints during each oil change (especially if it's scheduled every 5,000 miles) to ensure consistent upkeep and avoid forgetting.

It's important to note that many modern vehicles use sealed U-joints without grease fittings, meaning they are lubricated for life and cannot be serviced. In such cases, the joint must be replaced once wear begins. Always consult your vehicle’s service manual to determine whether your U-joints are serviceable and what the manufacturer recommends.

The lifespan of a U-joint varies widely based on maintenance, vehicle type, and driving habits:

• Average Lifespan: With proper lubrication and moderate driving, most U-joints last between 70,000 and 100,000 miles.
• Well-Maintained Joints: In ideal conditions—regular greasing, smooth driving, and no excessive loads—some U-joints can exceed 100,000 miles without issues.
• Shortened Lifespan: Harsh use such as frequent towing, off-roading, aggressive acceleration, or lack of maintenance can reduce life to 40,000–60,000 miles or less.
• Sealed vs. Serviceable: Sealed U-joints may fail earlier if contaminants enter or internal grease breaks down, while serviceable joints can last longer with proper care.

Regular inspection during routine maintenance (e.g., tire rotations or undercarriage checks) can help identify early signs of wear—such as looseness, rust, or cracked seals—before complete failure occurs. Replacing a worn U-joint promptly helps maintain drivetrain efficiency and prevents damage to related components.