Transfer gear

Types of Transfer Gear

Transfer gear is a vital component of a vehicle's transfer case. The transfer case is situated between the gearbox and the axles in four-wheel and all-wheel-drive vehicles. It helps distribute the engine's torque to the driving wheels. Transfer gear ratios influence the vehicle's performance, affecting aspects like low-end torque and high-end speed. Different types of transfer gears are as follows.

• Crown Wheel and Pinion Gears

  Crown wheel and pinion gears are the most common transfer gears in vehicles. They are highly preferred because they offer a quiet and smooth operation. The transfer case uses these gears to change the direction of the power flow from the transmission to the axles. The crown gear is connected to the axle shafts, while the pinion gear is connected to the driveshaft. The pinion gear interlocks with the crown gear, allowing the rotational movement of the two gears.

• Helical Gears

  Helical gears are also used as transfer gears in many vehicles. They are designed with teeth that are set at an angle to the gear axis. The angled teeth enable helical gears to mesh smoothly with other gears, resulting in a gradual engagement of the teeth. As a result, helical gears generate less noise and are more durable.

• Straight Cut Gears

  Straight-cut gears are designed with straight gear teeth. The teeth are parallel to the gear axis and aligned in a straight row. This design makes straight-cut gears less efficient than helical and bevel gears. The inefficiency is attributed to the abrupt engagement and disbandment of the teeth, which leads to more wear and tear. Nonetheless, straight-cut gears are more durable than the other two transfer gears. This is because they are made from hard-wearing materials. They are also inexpensive.

• Spiral Bevel Gears

  Spurl bevel transfer gears are used in cases where space is limited. They are a compact version of helical gears. Like helical gears, the teeth of spiral bevel gears are angled. However, the teeth are more tightly packed, allowing for a more compact gear system. Spiral bevel gears are best suited for small cars.

• Hypoid Gears

  Hypoid gears are similar to spiral bevel gears. However, they are more efficient than spiral bevel gears. The main difference between the two gears is the position of the pinion gear relative to the shaft. In hypoid gears, the pinion gear is below the axle shaft. This design allows more contact between the two gears, making hypoid gears more efficient than spiral bevel gears.

Specification & Maintenance of Transfer Gear

The specification of transfer gears can be based on the type of gear and the application it will be used for.

• Transfer gear design: The gears are designed to give accurate and smooth transfer of power and motion. They are made of high-quality steel for strength and durability. The teeth of the gears are precisely cut to give accurate engagement and reduce noise and vibration. The surface of the gears is treated to improve wear resistance and strength. Transfer gears come in different sizes and ratios depending on the application.
• Application: Transfer gears are used in different applications. For example, in four-wheel vehicles, they are used in the transfer case to split power between the drive axles. The size and ratio of the transfer gear in this case is determined by the vehicle's make and model.
• Load capacity: Transfer gears are designed with load capacity depending on the application. For instance, in heavy trucks, transfer gears are designed to handle high loads and torque.
• Quality standards: Transfer gears are manufactured based on different quality standards. For instance, they are made to meet international standards like ISO and SAE standards.

Transfer gear maintenance is important in keeping the gear function and performance in good condition. Here are some maintenance tips:

• Transfer case service: The transfer case should be serviced as per the manufacturer's recommendations. This includes flushing the transfer case and replacing the fluid. This helps remove any debris that might have accumulated in the transfer case.
• Inspect transfer case: A transfer case inspection should be done to check for any leaks or damage. The seals and gaskets should be replaced if worn out to prevent leaks. The gears and bearings should be inspected for wear and replaced if necessary.
• Drive shaft service: The drive shaft should be lubricated to keep the U-joints and slip yoke in good condition. The drive shaft should be inspected for balance and alignment. A balanced and aligned drive shaft ensures smooth transfer of power.
• Wheel hub assembly service: The wheel hub assembly should be inspected for wear and damage. The bearings and seals should be replaced if worn out.
• Axle shaft service: The axle shaft should be inspected for wear and damage. The axle shaft should be lubricated to ensure smooth operation.
• Torque converter: The converter should have its fluid changed as per the manufacturer's recommendation. The gear shifting should be checked to ensure it works smoothly.
• Transfer gear ratio: The transfer gear ratio should be adjusted if necessary. This is done to optimize performance.

How to Choose Transfer Gear

Choosing the right gear transfer system requires careful consideration of several factors:

• Torque Requirements

  When selecting transfer gears for a particular application, it is essential to analyze the torque needs. The maximum torque that the gear system can produce without slipping or failing should be determined. Consider the gear ratio and the power capacity of the gears when calculating the twisting prerequisites.

• Space Considerations

  Transfer gear systems must be sized appropriately for the applications in which they are to be installed. Space limitations may affect the selection of gear size, housing design, and layout. Consider all aspects of the gear system, as well as the mounting options for the transfer gear, to ensure that they fit into the available space.

• Installation and Maintenance

  Transfer gear systems must be simple to install and maintained in order to minimize downtime and work costs. Consider the accessibility of the gears, the ease of mounting and aligning the system, and the expected maintenance requirements, such as lubrication and adjusting gear clearances.

• Vibration and Noise

  Transfer gears are a common source of noise and vibration in mechanical systems. For applications where quiet operation is essential, such as in automotive interiors or precision machinery, gear designs and mounting arrangements that minimize noise and vibration should be considered.

• Environmental Factors

  Transfer gear systems can be affected by environmental factors such as temperature, humidity, and exposure to corrosive substances. Selecting materials and lubricants suitable for the operating environment is crucial to ensure the long life and reliability of the gear system.

How to DIY and replace transfer gear

Replacing the transfer gear set is no easy task. Because the transfer case sits between the axles, mechanics must first lift the vehicle. This requires a jack and jack stands. The mechanic will also need to disconnect the battery's negative cable. Working on the transfer case requires the use of hand tools, including a ratchet, sockets, combination wrenches, and extensions. A screw extractor may be needed to remove broken fasteners. The mechanic will also need to drain the transfer case of its lubricating oil.

The lubricant must be drained because the transfer case will be opened during the gear replacement, and the oil inside will spill out. Once the oil is drained, the mechanic can unbolt the transfer case and remove it. The next step is to remove the old transfer gears. This is the part that requires a lot of care. Gears are precision parts, and even a small mistake can affect their function.

As a last resort, the mechanic may have to use a gear puller to remove stubborn gears. Before installing the new gear set, the transfer case must be cleaned thoroughly. Afterward, the mechanic will install the new gears and bolt the transfer case back on. The final steps are to refill the transfer case with oil and reconnect the battery.

Because of the complexity of transfer cases and gears, it is always advisable to hire a professional mechanic to do the replacement.

Q&A

Q1. How often should the transfer gear be replaced?

A1. There is no set time for when the transfer gear should be replaced. It depends on the extent of wear and tear. Signs of a worn transfer gear include noisy operation and difficulty in gear shifting. When the transfer gear case shows gear shifts becoming hard, the transfer gears should be checked for damage.

Q2. Can users upgrade transfer gears for better performance?

A2. Yes, it is possible to upgrade the transfer gears. However, it is advisable to seek professional help when considering an upgrade. The professional will determine whether the upgrade is compatible with the current transfer case.

Q3 Are transfer gears the same in all vehicles?

A3 Transfer gears are not the same in all vehicles. The size and type of transfer gears depend on the vehicle’s make, model, and specifications. However, similar vehicle models have the same transfer gears.