AS9120B, ISO 9001:2015, and FAA AC 0056B ACCREDITED

How do Hydraulic Clutches work?

Hydraulic clutches are a common assembly that may be found within various types of vehicles made after the 1990s, and they utilize hydraulic fluids to adjust a clutch disc. With fluids, the hydraulic clutch will actuate a hydraulic piston, that of which will then engage or disengage the clutch using a series of connections. By converting clutch pressure into hydraulic pressure with the clutch brake cylinder, power can be transported to the clutch slave cylinder. This allows for a rod from the slave cylinder to actuate a clutch fork, that of which moves the clutch release bearing. As a result of these operations, the clutch pressure plate is released so that the clutch may be disengaged.

In vehicles containing integral antilock brake systems where the hydraulic control assembly contains a piston chamber, power assist is supplied by an electrical pump with a nitrogen pressurized accumulator. In order to ensure ample power assist, pressure is stored within the accumulator for use as required. When one is driving and they depress the brake pedal with their foot, a pushrod will be adjusted forward to open up a valve that is situated within the hydraulic brake cylinder. By doing this, stored pressure from the accumulator will be transferred into a cavity that is present behind the piston assembly. As pressure enters the cavity, it will force the piston forward, allowing for the vehicle’s brakes to be applied.

While such modern assemblies are quite reliable and advanced, they can face issues over time that result from various problems. Generally, the most common issues faced by hydraulic clutch assemblies include fouled pump motors, leaky accumulators, piston chamber assembly internal problems, and more. Generally, these issues will cause a diagnostic trouble code (DTC) to appear on the ABS or brake warning lights. This is because the assembly is a part of the ABS. If there is an issue with the electric pump or accumulator, each can be replaced separately from one another. However, if the brake cylinder and hydraulic control unit are combined, then one will need to replace the entire assembly at once if issues ever arise. Due to the complexity of these assemblies, replacement can be more expensive than if you were to just replace one element or the other.

If you are trying to decide between a vehicle with or without a hydraulic clutch, there are various factors to keep in mind. In terms of advantages, hydraulic clutches offer an easier pedal press, smoother engagement, and no need for adjustments during operation. Despite this, they do require bleeding, and as stated before, their replacement can be costly. As a result, they are most popular with drivers who want the most modern technology available on the market, or when one does not want to adjust the clutch at all. With their potential issues, it is important to note that most small repairs are fairly easy to conduct when compared to other options, though leaks can be a bigger issue that can cost more to treat. Additionally, the clutch brake cylinder and slave cylinder can also be more complex to treat in certain instances. As previously mentioned, hydraulic clutches will need to be bled from time to time, generally once every few years. Luckily, this is a fairly simplistic process that can be handled by a single individual.

Vehicles can also be upgraded to a hydraulic clutch if one so desires, and it is a fairly affordable endeavor despite the more complex process. The first step is simply to remove all linkage components that are currently in your mechanical set-up, and the firewall will need to be drilled through in order to mount and connect the hydraulic cylinder. After this, the clutch slave cylinder will need to be installed and connected to the hydraulic brake cylinder. Then, the reservoir can be installed before bleeding the clutch for the first time. After this, you can test the treadle, and it should feel very smooth throughout its movement. If it stands still or cannot return to its resting position, there is an issue that should be resolved before trying to drive.

If you are interested in procuring hydraulic clutch components for a brand new installation or for replacement, look no further than Acquire NSN. Owned and operated by ASAP Semiconductor, we present customers access to over 2 billion new, used, obsolete, and hard-to-find parts that have been sourced from leading global manufacturers that we trust. Every item on our database is ready for purchase at any time, and you are encouraged to fill out and submit an RFQ form at your earliest convenience for any items of interest. Once we receive and review a request, a member of our staff will reach out to you in 15 minutes or less to provide a customized solution that caters to your needs. Kick-off the purchasing process today and see how Acquire NSN can meet and exceed your expectations!


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