Thread: Telma Brake Retarders
10-12-2000, 04:15 PM #1TelmaJoeFirehouse.com Guest
Telma Brake Retarders
Just curious to know some of your thoughts on the Telma Brake Retarder system...any comments and or suggestions would be sincerly appreciated. If you're not sure what a Telma is, please refer to www.telmainc.com. Thanks again.
10-12-2000, 04:54 PM #2NUMBYFirehouse.com Guest
I personally havent been on a truck that used one. So i dont have any experience. When we got a new truck last year the committee looked at all of the different secondary braking systems and decided to just have an exhaust brake system. One of the other departments close by has the Telma brake retarder, and from what i hear they dont like it. Most of them say that when it engages it is very rough and jerks the truck pretty hard...like its gonna toss em through the windshield. But once again this is not my experience.
Anything i say in the forums is my opinion and does not reflect my department or any organization i belong to.
10-13-2000, 12:22 AM #3ArmyTruckCompanyFirehouse.com Guest
I do not like the Telma system at all- As the previous post mentioned, I have expierienced "jerking" and rough motions....One other disadvantage of the telma system is it's enormous appetite for electricity and it's creation of huge amounts of heat.
The overall best auxiliary braking system in my opinion, is undoubtedly the internal hydraulic system in the new Allison World Series transmissions....When coupled to a Detroit series 40, 50 or 60 motor, the performance of these units are outstanding!!! But you do pay the price. I have also driven jake brake equipped trucks as well as a series 40 detroit with an exhaust brake- that wasnt bad either.
10-13-2000, 12:33 AM #4Halligan84Firehouse.com Guest
We've been running 3 of them for the past 6 years and love them! I have never driven anything that stopped as fast and smooth and straight. We looked into them all and drove them all and thought the Telma was the best performer and still feel that way. We hooked ours up with ABS and 4 wheel disc brakes. When we let off the accelerator 2 stages come on, as you hit the brake the final 2 stages come on. On paper they do use alot of juice, but that is mainly in the 4th stage and momentary. The one post I agree with is the part about going through the windshield, if you were like me you were used to trucks that didn't stop when you tell them to, I think our rigs can stop quicker than some cars.
11-08-2000, 06:18 PM #5462co4Firehouse.com Guest
we have 2 trucks w/retards in them-sorry retarders installed on them-work great!!!
i wouldn't order another truck without it. as far as eating electricity, if your not going on a run and your sitting in traffic or whatever, they have an on/off switch! if you're used to driving trucks w/jakes and standard trans you know how to flip switches quick. my only complaint is where the switch is installed is not uniform!
11-23-2000, 12:09 PM #6Rick1403Firehouse.com Guest
We had Klam drive line retarders installed on our 2000 gal tankers 4 years ago. Driver training is a must! You can use the retarder or brakes on icy roads, but not both. 1st. year member driving tanker with the chief to a trailer fire, slide off the icy road and rolled 1 1/2 times. No major injuries, but threw a monkey wrench into the response.
Once you get past the training issue, I think they are great, with driver controled selection on the amount of braking applied, I can stop the tankers without touching the service brake.
There is trade offs to everthing, electrical loading and heating are to be considered. We are requiring our drivers to have a CDL license, most have an A endorsment, we talked about jake brakes, but felt unseasoned drivers would have a hard time with them.
We felt so strong about the Klams, we ordered it on our 75' Quint. Our Smeal is 39'6" long 48,800 lbs loaded, try stopping that without the Klam!
All in all I do not feel you can go to far wrong with a driveline retarder, it definitenly extends brake pad life.
12-23-2000, 02:08 PM #7fire127797Firehouse.com Guest
Our new pumps are equipped with the Jacobs Engine Brake and it works extremely well. The pumps have Series 60 Detroit Diesels and Allison WTEC transmissions, a great combination. Use of the service brake in good traction conditions is greatly reduced. SOP is to use the Jake in good traction conditions only. EMS in town uses the Thelma system on their modular ambulances and most of the paramedics prefer to NOT use the system. Too jerky.
10-10-2005, 04:22 PM #8
- Join Date
- Oct 2005
Retarder vs Engine Brake
I work for a small fire district in N.Ca in a very steep and hilly area. We have 3 E-One's on International chassis with Telma Retarders on them. Also, we operate a fleet of 4 Ambulances, 3 Fords, 1 Chevy with the Duramax/Allison combo.
The only issue with the Telma's on the Engines is the reduction in ground clearance because of the mid-shaft location. In the highest retard setting, you do really see the volt gauge drop. 2 of the Ford Ambulances have Telma's and they function great, no shudder/shake/jerking, and none of the voltage problem like the Engines (maybe due to the larger alternators?). The Chevy has just the standard pickup-style Allison and is going through a complete set of brakes at about 15K miles (front and rear rotors/pads/calipers).
I would highly recommend the Telma for areas experiencing high-brake usage. As for the combo of Retarder/Jake, wow...That would be some serious torque on the drivetrain and in anything but idea conditions, could cause vehicle instability.
10-10-2005, 05:50 PM #9Originally Posted by TelmaJoe
About the posts of the "jerkiness", sounds like an installation problem. I have personally driven everyone of our Telma equipped trucks and have not experienced a jerking. The only thing close to what you're describing is on our last 5 trucks the transmission was interfaced into the Telma (now NFPA required) and these two coupled can cause a pretty quick deceleration.
Telma's are four stage retarders. Our's are set as the first stage activates upon letting off the accelerator, the second stage activates at 5psi brake pedal pressure, third at 7 psi, and fourth at 10psi. Each stage consumes 50 AMPS. This is the main downfall of the Telma, along with pretty high cost. A truck must be spec'd accordingly with a very large alternator.
Each retarder has it's own downfalls. Jake's cause noise (and some say valve train damage), tranny retarders can BOIL your fluid, and Telma's can fry your electrical system.
Like anything, you should research what works well for your area and spec your truck accordingly. For us, a Jake is the best fit for us.
10-10-2005, 08:20 PM #10
- Join Date
- Apr 2005
- Las Vegas,Nevada
Telma is a great retarder system if properly installed and the electricasl system is designed with it in mind. On a big rig the Jake brake is great. If you want the Telma on a big rig then go for the focal mount system which is attached directly to the rear axle input prior to the driveshaft in lieu of a midmount.
10-10-2005, 10:24 PM #11
- Join Date
- Nov 1999
This has been covered before and I got slammed for what I am about to say, but....... While the Telma is an option as an auxiliary braking system, it is not the best option in my opinion. My career department had numerous problems with them after they were retrofitted on some existing rigs (At that time) as part of trial period. Granted that was part of the problem, being retrofitted, but the additional drain on an apparatus electrical system is not worth it long term.
Try a Super Jake as an alternative, followed by a transmission retarder (Which I don't care for) before you go with the Telma.
Just my opinion and thoughts.Stay low and move it in.
10-10-2005, 10:52 PM #12
- Join Date
- Jul 2004
- Penn Valley, Ca
We have Telmas, Jakes, and transmission retarders. I would submit that a Telma is the best choice for a retrofit but the whole system must be engineered correctly. i.e. the alternator must be able to supply the current the Telma needs, and the transmission must be programmed to keep the engeine (hence alternator) running at a decent speed so it can generate that current. The Telma must cut off at low speed so it is not drawing a lot of power and doing nothing while the truck is idling. The truck must have adequate batteries to supply the transient draw down of the Telma when approaching a stop (which is very short if all of the above is already correct). It is simple math, if the electrical budget works out then the Telma will cause no problems.
Of course the Jake is the best choice and can be retrofitted on some engines. It causes no damage to anything and it works very effectively too. By far the best.
The transmission retarder is third because of its tremendous maintenance cost and the risk incurred of taking out the transmission with glycol contamination. The coolers must be replaced quite often and they are very expensive. Also even before EGR engines the cooling capacity to be dumping all that heat into your radiator both uphill and downhill was marginal. Not a very good choice usually but many people don't know better
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