| Author | Message | ||
| Sojourner (Jjimage)
Rating: |
To whom it maybe of interest…….to clear your conscious of how can to tell which air brake actuator use on your dual wheel axle? All DD3; Has double diaphragms over single piston & small roller release piston. Consist of 3 ports…service, parking, and locking. The high light of each ports & information are following; 1) Service port is applied from dry tank via brake pedal 2) Parking port is applied from reserves tank thorough inversion valve via “Push & Pull” valve 3) Locking port is applied from dry tank thorough inversion valve, “Push & Pull” valve and brake pedal……..need at least 70 psi to (3rd port on main casting that mount on axle housing) release locking balls onto actuator’s shaft so it can move freely back & forth. Some time you have to depress brake pedal after “Push & Pull” is push in to release mechanical binding or sticking. 4) Must keep good dust & moisture rubber-bellow cover over shaft to main housing to protect locking mechanism. 5) Make sure it’s locking mechanism is working to hold after drain park tank 6) Rebuild or replace unit if it has corroded locking mechanism. Rebuild consist of 2 diaphragms, seals, white lube and 2 clamps & bolts w/ nuts. 7) All DD3 have one port to each housing part, other word a port on each side of clamping bands. 8) Remember….contain NON-heavy-spring for parking. 9) If air is drained from park tank….then you are trusting locking ball to keep in park. http://www.bendix.com/downloads/service_data_sheet/024600.pdf Spring brake; Has double diaphragms & pistons. Consist of 2 ports…service and parking with vents hole in end cover. Usually heavier & longer than DD3 unit due to big spring. The danger of earlier version is removing clamping band nearest to end cover without tool fixture. However most all new version are factory crimp onto spring’s end “can” so it non-removable. It called “Crimp Seal Combination” or single clamp. Earlier unit are “Clamp Combination” or double clamps. 1) If no air in tank, it remain in park 2) Have 2 “Push & Pull” valve…one to over-ride incase primary & secondary tanks drop psi. 3) Less parts to fail 4) Must keep spring’s vent from taking in moisture & dirt…or it will rust & worn seal over rod. Conclusion; So the only IMPORTANT things to remember is to look for number of air lines connect to double diaphragms unit before determine your expense. 1) 3 line is NON HD spring type 2) 2 line is HD spring type Caution; before remove spring brake actuator from mount is to apply parking air to retract HD spring before loosen mounting bolts & pin. Other words disconnect parking drained (to avoid whipping) air line LAST step after remove from mount. I believe all of today trucks & buses are using SEALED “Piggy-back” spring can for parking or emergency. George Myers wrote good article on air brake. http://www.busnut.com/artgm06.html Good “Tip” links add to “my favorite”; http://www.prairietruckandtractor.com/repairtips.html http://www.haldex-midland.com/literature/default.asp?target=https://www.haldex-midland.com :443/toolbox/toolbox.asp? Manufacture & photos of spring brake; http://www.tsebrakes.com/omnifamily.html http://www.hbsna.com/Products/SpringBrakeproduct.asp?msi=28&sid=6B2A8D593E0F48EC8508CF16F1 0E2BAA Installation & handling of spring brake; http://www.haldex-midland.com/pdf/literature/L31171%2011-05.pdf Hope it clear or otherwise speak up. Am retired HD truck mechanic in 60’s & welcome update mechanic information. Back then they were mostly DD3s or single diaphragm with hand lever parking brake. Next topic is to replace DD3 for spring type if it possible. New design are may fit older coach???? FWIW | ||
| AL STRECK
Rating: N/A |
HERE'S A GOOD BRAKE QUESTION!!!! IS THERE SUCH A THING AS A CONVERSION KIT FOR CHANGING DRUM AIR BRAKES TO AIR DISC BRAKES?? BRAKES ARE ON A GILLIG CHASSIS MOTORHOME. THANK YOU IN ADVANCE!! ALSTRECK@HOTMAIL.COM | ||
| Donald Lee Schwanke (Dontx)
Rating: N/A |
Why me. As usually forgotten, the DD3 provides over three times as much emergency or park brake pressures compared to the little springs. You have NO way of knowing if one of your springs has broken when you park, if one is broken, and the other snaps you WILL roll down the hill in a hurry, no warning, NONE! The smart money if safety and/or stopping is important is on converting spring brakes to the much safer and more effective DD3! I would trust 6 locking balls over a little spring any day of the week! This safety is why buses were required to have them long after the expendable Class 8 trucks went with something cheaper and less effective. | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Don, I think he was asking about changing from DRUM to DISC brakes. There were several posts regarding this recently and the general consensus was that not no but h*ll no. Richard | ||
| Donald Lee Schwanke (Dontx)
Rating: N/A |
I read this part to mean differently: "Next topic is to replace DD3 for spring type if it possible. New design are may fit older coach????" | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
All right Don. We are both correct. I was replying to ALSTRECK (IS THERE SUCH A THING AS A CONVERSION KIT FOR CHANGING DRUM AIR BRAKES TO AIR DISC BRAKES??), and you were replying to Sojourner. LOL Richard | ||
| Donald Lee Schwanke (Dontx)
Rating: N/A |
I agree there, I think disc brakes on heavy equipment is long overdue. |
