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Electronic shifting for planetary gear hub

5 min read

Asked by: Sarah Coleman

How does the planetary gear work in an automatic transmission?

The planetary gear train is a mechanical system in which the gears are connected with a set of bands and clutches. When the driver changes gears, the bands hold one gear still while rotating another to transmit torque from the engine and increase or decrease gears.

How does a planetary gear system work?

As they rotate inside of the ring gear, the planetary gears create pitch circles that can be formed into a gear train that, in turn, is hooked up to input and output shafts. The input shaft will come from the engine and the output shaft will head to the driven wheels.

What causes planetary gears to fail?

Faulty design is not only the reason for gearbox failure, manufacturing and material handling can be one. In planetary gearbox, noise is usually no worse, and often better than standard gear-and-pinion reducers. Having smaller gears means a lower pitch line velocity than a comparably rated pinion and gear set.

Are there planetary gears in a transmission?

They also form the basis of the most common type of automatic transmission, known as the hydraulic planetary automatic transmission. Most modern automatic transmissions in the automotive industry use planetary gears.

How many planetary gear sets in a transmission?

The ten speed transmission has six forward under drive ratios (the input turns faster that the output), a direct drive ratio and three over drive ratios (the output turns faster than the input). Inside the ten speed transmission there are four planetary gear sets and six shift elements.

Which planetary gear sets can be found in an automatic transmission?

The Ravigneaux gearset is a double planetary gear set, invented by Pol Ravigneaux, who filed a patent application on July 28, 1949, in Neuilly-sur-Seine France. This planetary gear set, commonly used in automatic transmissions, is constructed from two gear pairs, ring–planet and planet–planet.

Are planetary gears more efficient?

In addition to their durability, planetary gear motors also provide a higher efficiency over spur gear motors.

Which component uses planetary gears?

Planetary gear train (PGT) has been widely used in the transmissions of helicopters, automobiles, wind turbine, aircraft engines, etc. The main advantages of this transmission are its high efficiency, its compactness, its large transmission ratio and its large power-to-weight ratio, etc.

Do CVT transmissions have planetary gears?

A CVT uses a simple pulley system rather than the planetary gears that can be found in a traditional automatic transmission. The CVT has an input pulley, an output pulley, and a belt connecting the two pulleys. These are conical pulleys with variable diameters.

How do you know if planetary gear is bad?

If there is buzzing, clunking, humming noise

A buzzing, clicking, humming, roaring noise from inside the transmission is usually a symptom of a bad bearing, planetary gears damage, or other internal problem. A buzzing could also come from a bad internal sealing surface, a seal, or low transmission fluid due to a leak.

How do you know if your planetary gear is bad?

Visual Signs of Planetary Gear Wear

Worn gear teeth that look more pointed that squared. Bent gear teeth. Cracking (this starts at the root of the gear teeth where the stress is the highest) Surface damage, such as pits, scuffing, or areas that look polished compared to their surroundings.

What are the two most typical failure modes for gears?

In an analysis of more than 1,500 gear failure studies, the three most common failure modes were tooth-bending fatigue, tooth-bending impact, and abrasive tooth wear [4].

What are the three types of planetary gearsets?

Three main types of the planetary gearbox are available based on their performance, including a wheel drive, shaft output, and spindle output.

Is a differential A planetary gear?

As already mentioned, a differential gear is a special type of a planetary gearbox. One of the bevel gears on the wheel shafts can be regarded as a sun gear while the other bevel gear then corresponds in a figurative sense to the ring gear.

How do you calculate gear ratio on planetary gear?

Calculate gear ratio by dividing the number of teeth on the driven gear by the number of teeth on the driving gear.

When should I use planetary gears?

Planetary gears are often used when space and weight are an issue, but a large amount of speed reduction and torque are needed. This requirement applies to a variety of industries, including tractors and construction equipment where a large amount of torque is needed to drive the wheels.

How does an automatic transmission work on a motorcycle?

Automatic Motorcycle Pros

The bike comes with a built-in computer that automatically shifts gears and the clutch based on riding conditions. Most automatic makes and models use a dual-clutch system for a smoother ride. If you’re new to riding a motorcycle, this is the style for you.

How does the planetary gear set increase or decrease speed and torque?

A planetary gearhead takes a high-speed, low-torque input, say from an electric motor, then increases torque and reduces speed at the output by the gearhead ratio. This lets motors run at higher, more-efficient rpms in equipment that operates at low speeds.

How does an automatic transmission valve body work?

The valve body is one of the pieces of equipment that allows an automatic transmission to function correctly. By channeling hydraulic fluid through a series of paths, the valve body is able to trigger the correct clutch pack for the selected gearing.

What causes transmission valve body failure?

Reasons for Transmission Valve Body Failure

One reason for failure is a poor oil pressure. Also, without a high enough pressure, certain valves won’t operate correctly, causing a chain reaction and poor functioning gearbox. This low pressure can be caused by low levels of transmission fluid or leaks.

What happens when a valve body fails?

The valves will wear down, the channels can be abraded and become oversized, and the whole valve body unit can become warped. Signs of a bad valve body can be fluid leaks, slipping during gear changes, or even failure to go into gear.