Can someone identify this component?

[frank-id]

Telma driveline brakes..
Google... https://www.google.com/search?q=electri ... =firefox-a

This device takes the place of a grade retard or Jake brakes. These devices are used on mountain areas and are used to save the main brakes. The units can get very hot and sometimes the friction disc will glow very red. When this type brake system needs some attention, many problems may occur. Some commercial bus operators remove the unit. The unit has value for those who need/desire the unit. The box controlling the electrical power needs special knowledge. Try Google for more information. For a short time I was searching for a unit. There are several models for different GVW vehicles. A good used unit is valued at about $750-1000. Frank

[Stuff]

up here those are illegal. puts strain on the U joints etc. cut her out!

[crazycal]

I have a similar problem with my bus. My vibration is caused by an out of balance, out of round front tire. This was caused by worn king pins. It started at 45 mph and stopped at 55 mph but you said you checked that. If you can safely jack up the bus andrun it in drive, maybe you can see if the disk on the Telma unit is out of round.

[bansil]

By looking at the pic,several of the fins between hub and outer rotor look broke,that would def. Cause a vibration...make sure to chock tires when you pop driveshaft off...I have seen them roll

[kotflb]

B4 you remove that retarder look up Telma and other drive line retarders and see what they have to say. You can use that device anywhere you use your brakes, not just in the mountains. One thing to try b4 you go any further is to lube all your driveshaft U joints often and well, because vibration is one thing that will cause a retarder to become un balanced and malfunction. I would keep it on the bus if it were mine. It can extend your brake shoe life by 400 to 500%, saving you a lot of money on parts and labor.

You should have a on-off toggle switch with a small light nearby somewhere on you dash to turn it on and also have a small shift lever either in your steering column or around the dash that has 5 positions. The toggle switch sends power to the small shift lever in 4 of the 5 positions. You can see a demo on you tube.