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A clutch brake is a circular disc with a friction surface that is splined to the input shaft of the transmission between the release bearing and transmission. Its purpose is to slow and/or stop the input shaft from turning to allow initial forward or reverse gear engagement in non-synchronized transmissions. It helps prevent premature wear of the internal transmission parts during those initial shifts. To understand this in more detail, let's consider what is going on when a heavy truck transmission is shifted from neutral to first or reverse. When a truck is in neutral and the clutch pedal is not depressed, the master clutch is engaged. This causes power from the engine to drive the transmission input shaft, resulting in rotation of some shafts and gears in the transmission. However, the gears aren't engaged or meshed in a way that transmits power to the drive shaft. In other words, parts of the transmission are just idling but spinning.
When the clutch pedal is depressed, it moves the release or throw-out bearing toward the transmission and away from the flywheel. This unloads the springs in the master clutch, releasing the master clutch and decoupling the flywheel from the transmission output shaft.
Without the engine driving the transmission input shaft, the spinning shafts and gears in the transmission start to coast down. However, it would take a long time for these rotating masses to slow down, because they have a lot of mass and the only thing that is slowing them is gear and bearing drag.
If everything is properly adjusted, the master clutch is opened or released when the pedal is depressed about half way or so.
If there's no clutch-brake, and you then shift into first or reverse, the rotation of gears in the transmission won't all be the same on a non-synchronized transmission, and then the gears can clash or make a "thunk" as gears that are spinning are meshed with gears that are not spinning. Over time, this can wear or even damage the gears.
When a clutch-brake is installed, pushing the clutch pedal all the way to the floor pulls the release bearing even further away from the master clutch toward the transmission, which eventually squeezes the clutch-brake disc between the release bearing and the transmission case. Friction between these parts then slows and soon stops the transmission input shaft from rotating.
Now, gears can be moved into mesh in the transmission and there might be a bit of noise because the teeth aren't perfectly aligned, but they won't be rotating. If you time everything just right, you'll make the shift from neutral to first or reverse just as the gears are almost stopped, but not quite. A little rotation helps ease the meshing and can almost eliminate noise or "thunk" sounds.
The clutch-brake is unusual because it always picks up grease from the release bearing. Modern clutch-brakes are designed to operate with grease, and they even require greasing or oiling before installation.
Clutch-brakes fail for two reasons. First, over time, the friction material will wear out. At some point, there will be metal-to-metal contact in the "sandwich" consisting of the bearing, clutch-brake plate, and the transmission cover. This might still slow the gears, but it can cause damage to the bearing or the transmission cover. It's also possible that the release bearing won't be able to move far enough toward the transmission to squeeze the disc, and the clutch-brake won't slow down the transmission shaft because there won't be friction in the "sandwich."
If you keep the pedal linkage properly adjusted and periodically grease the release bearing and clutch-brake disc, the disc can last for a long time.
However, the most common cause of clutch-brake failure is depressing the clutch pedal all the way to the floor when shifting during a range change--when the truck is moving. When you do this, you are forcing the little clutch-brake to try and stall the engine and stop the truck! Doing that only one time will often destroy the clutch-brake completely. This can also occur if the pedal linkage isn't properly adjusted and the release bearing squeezes the clutch-brake into the transmission case when making a range gear change.
Wiki User
∙ 14y ago
Wiki User
∙ 12y agoIt is a brake that stops the input shaft on the transmission from spinning when you depress the clutch pedal all the way to the floor.
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A lever Wheels and axles An inclined plane (when the truck dumps out its contents)
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inclined plane
How often use the clutch brake in a semi truck?
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What is a clutch brake used for on a tractor trailer truck?
When you depress the clutch pedal all the way down the clutch brake stops the input shaft from rotating. This allows the transmission to be put in gear. Never depress the clutch fully ( all the way to the floor) when the truck is moving in any gear. The clutch brake is about the size of a compact disc and cannot stop the input shaft when the truck is moving in gear. This will destroy the clutch brake.
What is a syncor mesh in an automobile?
Synchromesh is reference to a manual transmission,gears are synchronized (one gear is brought to the same speed of rotation as another)before the teeth actually mesh.Almost all modern manual transmissions are fully synchronized.Most heavy truck transmissions are not,that is why you have to double clutch the shifts.
What type of clutch fluid for a dodge 1959 pickup?
A 1959 truck has a mechanical clutch. A 1995 truck uses Dot 3 brake fluid for the hydraulic control.
How do you adjust clutch brake on eaton fuller?
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How does a clutch break work?
If a truck has a clutch brake it would only be used when coming to a complete stop. By pushing the clutch peddle completely to the floor you would apply the clutch brake. This stops the clutch disc from spinning making it easier to shift into 1st or reverse gear. Normal shifting while driving you would not need to or want to push the clutch peddle to the floor to activate the clutch brake.
Does 1987 Comanche jeep truck use clutch grease?
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Does it have a manual transmission with a hydraulic clutch ?
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The clutch start cancel button will eliminate the need to press the clutch in to start the truck. This is useful in mostly offroad situations where pushing in the clutch to start the truck might allow the truck to roll from a precarious position such as off of a rock or back down a hill. You are starting the truck "in gear" so that there is no jerky movements with engaging the clutch. This works best when in the transfer case is in Low. The front hubs should also be locked. To use when on a steep hill or crawling over rocks: * keep your foot on the brake. * press the clutch start cancel button. * turn the key to start the truck. * as the truck begins to move, ease up on the brake to allow the truck to move forward and start. * as the truck starts apply the accelerator pedal as needed to keep you going and prevent stalling. * If you stall it's OK, just keep using the clutch start cancel button until you are out of the situation
What type of clutch fluid is required for a 1988 Chevy half ton truck?
Dot 3 brake fluid is just fine and safe.
Why does your truck shake violently when you start to release your clutch?
Assuming you mean "engage the clutch" or "Release the clutch pedal" which is the exact opposite of what you actually asked: 1) clutch disc contaminated with grease/oil/brake fluid 2) engine misfire (is RPM high enough?)
What is transmission inertia brake Eaton K3637 NIB?
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