American friction cobra brake blocks
DO NOT be worried or concerned that these blocks don't look like what you're used to seeing.
These are NOT the same blocks you've come to know as "hard blocks",
"scraper blocks", or "wiper blocks", etc.
They have been specifically designed to completely replace the "soft woven type" blocks you've always known.
They WILL NOT glaze if you get them hot; unlike a non-asbestos
"fiberglass based" woven block you've used before.
After installation, please confirm that the top 3-4 blocks are not touching the brake rims. (Lift your brake handle all the way up (brakes disengaged).
The first 3 blocks above the equalizer at the "dead end" should not be touching the brake rims! If they are, adjust the rollers under and behind the bands!
We recommend burning them in (some like to call it "burnishing") just like you've always done (or tried to do) with woven blocks. (see more détails on the relining instruction sheet enclosed)
AMERICAN FRICTION MANUFACTURES THESE BLOCKS IN HOUSTON, TX. AND WE STAND BEHIND THEM 1000%
CALL US AT 780-440-0132 WITH ANY QUESTIONS.
brake block general relining instructions
(Applies To American Friction "COBRA" Brake Blocks only)
April 26, 2023
- Make certain bands are clean and free from rust, grease, paint and primer.
- Warped or sprung bands should be rolled or trued up.
- Do not paint or prime inside surface of the band as this will reduce the "static" friction between the blocks and band and will hinder heat transfer.
- Install bolts and nuts in center of blocks first (do not tighten before outside bolts have been installed). Tighten (torque) the inside bolts first, then the outside. In this way the block will conform to the radius of the band. Sometimes a C clamp will be needed in the center of the block (or at the ends) to pull it into the band while installing bolts or tightening.
- Tighten 3/8" bolts to 23-26 foot pounds of torque maximum! Tighten 5/16" bolts to 15 foot pounds of torque maximum! Over tightening will result in damage to the bolt.
- After tightening the bolts, "center punch the bolts at the point of nut and bolt contact. If you are using "Star washer" nuts, the nuts will almost certainly back-off due to vibration if this procedure is not followed. We DO NOT recommend "peening" the bolts at their ends. This procedure will NOT keep the nut from backing off, because the "peening" is not done at the nut and bolt contact, but merely at then end of the bolt.
- Be sure both bands are equalized correctly after installation of the bands over the rims. If you have any concerns on exactly how to do this - contact us.
- "BURNING IN" OR "BURNISHING": We do recommend that you perform this operation after a new installation. Our COBRA blocks will actually work better after they become hot during this operation and from then on. The blocks will not be damaged or "glazed" by this operation.
We recommend that you check your rims frequently. We recommend at least every six months (or more often) on an active rig. Place a steel straight edge (a steel ruler works great) along the width of the rim. If you can see daylight in the amount of 0.005" - 0.020" (0.127 mm
- 0.508mm) we recommend a "burning in" procedure (with new blocks) before putting the rig to work. If there is daylight greater than this, we recommend replacement of your brake rims.
Anything greater than 0.005" of wear across the width will increase the time if takes for the driller to achieve 100% contact between the blocks and the rim surface. Only after 100% contact is achieved will the driller have his full potential in braking performance. If you have any questions please contact us.
AMERICAN FRICTION, INC.'S LIMITIED WARRANTY
1. AMERICAN FRICTION, INC WARRANTS THAT ITS PRODUCTS WILL BE FREE FROM DEFECTS IN WORKMANSHIP AND MATERIALS FOR A PERIOD OF ONE YEAR FROM THE DATE OF SHIPMENT. NO OTHER EXPRESS WARRANTY IS GIVEN AND NO AFFIRMATION OF AMERICAN FRICTION, INC., BY WORDS OR DEEDS, SHALL CONSTITUTE A WARRANTY.
2. FOR BREACH OF ANY EXPRESS OR IMPLIED WARRANTY THE PURCHASER IS LIMITED TO THE FOLLOWING DAMAGES: REPLACEMENT OR REPAIR OF THE GOODS SOLD, AT THE OPTION OF AMERICAN FRICTION, INC. AMERICAN FRICTION, INC. IS NOT AND SHALL NOT BE RESPONSIBLE FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES.
3. THIS WARRANTY EXTENDS TO THE ORIGINAL PURCHASER OF THE PRODUCT AND SUBSEQUENT PURCHASERS ARE NOT COVERED BY THIS WARRANTY.
DISCLAIMER OF IMPLIED WARRANTY OF FITNESS
AMERICAN FRICTION, INC. DISCLAIMS ANY WARRANTY OF FITNESS FOR ANY PARTICULAR PURPOSES WHATSOEVER.
DISCLAIMER OF IMPLIED WARRANTY OF MERCHANTABILITY
IT IS SPECIFICALLY AGREED THAT THE GOODS SOLD BY AMERICAN FRICTION, INC. ARE SOLD WITHOUT ANY WARRANTY OF MERCHANTABILITY.
