Maintaining Guide Manualof the Air Disc BrakeContentCATALOGUE1. Summarize2. Maintaining description2.1 Safety briefing during maintaining2.2 Breaking function check2.2.1 Clearance check2.2.2 Adjuster check2.3 Brake pads check2.4 Rotor check3. Brake pads replacement4. Brake replacement5. Dust cap replacement5.1 Dust cap & bushing replacement5.2 Screw dust cap replacement6. Rotor check/replacement6.1 Rotor check6.2 Rotor replacement7. Brake chamber replacement7.1 Brake chamber removal7.2 Brake chamber installation8. Adjuster replacement9. Troubleshooting10. Exploded view11. List of mounting & maintaining toolsBrief introduction of YOUFINYOUFIN was established on May 20th, 1998. It is a Sino-Foreign joint-venture enterprise registered in Wuhan Economic and T echnological Development Zone with multi-investors among which private investors dominate. It is a professional company engaged in manufacturing disc brakes and serving the principal automobile manufacturers by providing modularized supply. The main prod ucts cover hydraulic disc brakes and air disk brakes in close to thirty sizes.YOUFIN developed the air disc brake autonomously and patented the product. So far we are the only manufacturer in China that can mass produce air discs to be used in long distance coaches and inner city buses. It is evaluated that the quality of our products is close to the advanced international level in field use. The product development is part of the National T orch Plan and is also sponsored by the Small and Medium-sized Enterprise T echnical Innovation Foundation of Chinese Ministry of S&T.Our Air Disc Brake products are on an absolute leading position in China and the same international level as far as the key technology is concerned.1. SummarizeYOUFIN Air Disc Brake has four sizes (16’’, 17.5’’19.5’’, 22.5’’). It can satisfy different vehicles. The brakes have compact structure; automatically wear compensation and can easily changing the brake pad.2. Maintaining descriptionSafety briefing during maintainingIt’s most important to ensure safety driving and breaking by goodcharacteristics of the brake.Observe brake pad and rotor wear limits. When they warned already to assigned smallest thickness, it need replace immediately, otherwise, it may cause the accident. The pads scorches, grinds or greases must replace immediately.Every pad on each bridge must replace at the same time.When services the brake, the vehicle must park in smooth gound and the wheel withstand with the block/ stone prevent rolls.Note:●Must guarantee it does not occur with careless brake. When replace brakepad don’t make the brake, otherwise, it will hurts the body!●Do not use the compressed air or other cleaning up equipment clean thebrake, in order to avoid injures the body.●Be sure your hands and fingers place outside the caliper, in order to avoidinjures the body.●When moves and installs the brake should have some assistance, avoids ittoo heavy to hurts the body.●When take off the brake to make maintenance, it must fix on the clamp withhigh strength bolt, in order to avoid hurts the body.●Only allowed genuine YOUFIN kits and pads permitted by YOUFIN. Duringthe first 50 miles driving after new pad replacement, should avoid promptlybrake and brake at a long distance, Prevent overhigh temperature.●Allowed genuine YOUFIN kits and brake pads permitted by YOUFIN.●Only can use the recommendation kits in service. Screws the bolt/nutaccording to the request moment of force.Brake Function checkClearance checkProcess:●T ake off the hexagon bolt (39), loosen the pad retainer (38).●Remove pad retainer (38) from caliper.●Remove 3pcs of pad clip (37).●Move the cable (40) to the side.●Push the caliper towards the wheel and check the clearance with tune-upgauge.0.5mm ≤ clearance ≤ 1.2mmNote: Insert tune-up gauge between the caliper (1) and the brake pad (35). Should check the adjuster while the clearance is out of standard.Adjuster checkProcess:●Remove the rubber cap (12).●Turn hexagon head (22) clockwise by wrench to ensure clearance larger than3mm. (Or remove the brake pad and the push board)Note:a. Need enough room (3mm<clearance) for turn adjuster preventing un-fit.b. Never force to adjust the hexagon head (22) and/or the adjuster!Push the pressure arm 5 times in small increments and observe the hexagon head (22). While the adjuster is in good condition, hexagon head (22) must rotate clockwise.c. As the regulated quantity increase, rotation angle decreases.If the adjuster hexagon head (22):a) Not running at allb) Only running at first pushc) Running, but stopped in the middleWhile considers adjuster failed. Y ou should replace the brake on the basis of section 4 or change the adjuster in accordance with section 8.●Keep the clearances at 1mm (section 3) after adjuster check is finished.●Reinstall the rubber cap (12).Brake pads wearing check●Scorches, grinds and greased brake pad must replaces immediately.●Brake pads at the same bridge must replace at the same time.●Brake pad and pad clip must replace at the same time.Rotor checkProcess:●Remove the brake pad according to section 3.●T est thickness of the rotor.Note: Observe the brake pads and the rotor attrition situation. Excessive attrition of the rotor and the brake pads will reduce their potency and causes the brake fail!CAUTION: Rotors on the same bridge must replace at the same time. Single side rotor replacement is unacceptable. Recommend installs new brake pads whilereplace the new rotors.Rotor Dimension limitsRotor jumpiness (↗) check:2.4.1 Process:●Installs division indicator on the bracket (dial guage).●Measure jumpiness (↗) through turns the wheel. Jumpiness (↗) should lessthan 0.15.●Replaces the rotor to satisfy the request of section 6.●Modified brake pad should fulfil the specific requirements in section 3.2.4.2 Rotor test:At each change of Pads check the Rotor for grooves and cracks.The diagram at the right shows possible conditions of the surface.A = Small cracks spread over the surface are allowedB = Cracks less than 0.02in. (0.5mm) wide, running in a Radial direction, are allowedC = Grooves (circumferential) less than 0.06in. (1.5mm) wide are allowedD = Cracks in the vanes are not allowed and the Rotor MUST BE REPLACED.a = Pad contact area3. Brake Pad replacementNote: Do not use the pipe spanner/ board die! Keep your hands and fingers outside the caliper avoid the hurts of body!Brake Pad dismantle process:●T ake off hexagon bolt (39) from the Pad Retainer with spanner.●Remove the pad retainer from caliper (1).●T ake off the pad clip (37), which is above the pads (35,36) and push board (19).●Remove the sensor on brake pad.●T ake off the push board (19) & the brake pads (35,36).●Adjust hexagon head to make tappet back to the initial position.●Clean the pad groove & push board and anchor surface with brush.Note: Don’t hurt the dust cap (5 & 10). Be sure of no grease on installation surface!●Check the adjuster on the basis of section 2.2.2.Note: Fix the key while checking & turning the adjuster cap to avoid screw rotate.●Check the rotor according to section 2.4.3.2 Brake pad installing process:●Need enough room between the caliper & the rotor to insert brake pad.●Insert push board (19) at the place the caliper combine with the adjust screw.Note: Push board must on the bracket supporting surface. Adjust screw pin must in groove. Otherwise it will do harm to Adjuster mechanism. Ensure the dust cap untwisted by rotate the adjust screw.●Insert the cable sensor to pad groove. Fix cable on bearing (40).Note: The sensor contactor must face the brake disc and installs at the correctposition. Attention the wire trend to prevents the friction.●Insert new pad (36) at side of the push board.●Push caliper toward the wheel until the pad touch the rotor.Insert the brake padat wheel side.Note: Don’t adjust hexagon head violently.Note: Turn the adjuster counter-clockwise to decrease the clearance between pads.Don’t install the retainer before adjustment.Note: Check the rubber cap (12), be sure it is correctly seated.4. Brake replacementNote: Don’t use pipe wrench. Ensure your hands and fingers outside the caliperavoid hurt your body!Note: The Brake will supplies in assembly.CAUTION: The left brake and the right brake cannot exchange. Arrow direction on the brake is same as the forward direction of the wheel.4.1 Brake removal process:●Remove brake pad (see Section 3).●Release nut on the caliper, take of brake chamber.●Remove brake assessment from the bridge.●Check brake pad on the basis of section 2.3.●Check rotor on the basis of section 2.4.4.2 Brake installing process:●Install the new brake over rotor on the bridge. Screwed bolt with the spanner.Note: The right install order of the bolt is screwed both side symmetry.●T ake down the flange protection cap on the brake chamber.Note:Air chamber installment position. Open the scupper faces the ground, and stops other mouths.●Install brake pad and push board on the basis of section 3.●Install the air chamber and tighten with spanner.●Adjust the clearance.5. Guide Pin dust cap replacementNote: Do not use the pipe spanner/ board die! Keep your hand & finger outside the caliper, in order to avoid injuries.Note: When replaces all dust cap of guide bushing, section 5.1 & 5.2 should unify to avoids repetitive work. Single bushing replacement according to 5.1 and 5.2 corresponding work orders.5.1. Dust cap & bushing replacement●T ake off the brake pad according to section 3.●Loosen the chamber bolt and remove the brake chamber from caliper.●Remove the caliper assessment from bridge.●T ake off the steel cap (11) from guide bushing (8 & 9) by suitable tools.Dismantle caliper (1) from the bracket (2).Note: Don’t hurt the hole, the lid while open the steel cap with tools.●Loosen the bolt (6 & 7); separate the caliper (1) from the bracket (2).Note: When caliper moves, it may hurt body.●Cleaning up the bracket bonding plane●Take off the guide pin (8&9) on caliper (1). Then remove the dust cap (5).●Presses out bushing 4 with mandril from caliper1.●Cleans up the guide pin hole of caliper.Installing process:●Long guide pin hole must press in two new bushings. Short guide pin holepress in one.●Guarantee the size in drawing.●Greases between them and the bushing●Install new dust cap in the guide pin hole.Note: Cleans up the guide pin hole and grease the edge of dust cap before install for easy installation. Ensure the dust cap installs steadily, without crease and inside the ring groove of the caliper.●Install long/short guide pin to each hole and dust cap upside set in guide pinring groove.●Put the caliper (1) on the bracket (2) and plug guide pin (8&9) in guide hole.●Plug new bolt (6&7) (long one for pin 8, short one for pin 9) and screwed onbracket (2) with spanner.Note: Assembly must be careful, don’t damage the dust cap (5). First, screws bolt on long pin (8), and then screws bolt on short pin (9).When service maintenance, remove the guide pin (8&9) and replace by new bolt (6&7)!●Move the caliper on guide pin (8,9) forward and backward to check whether thecaliper can move freely.●Put on new copper cap on caliper (1) hole and push it in with correct kits. Note: Avoids the hurts of surface.●Raising the guide pin dust cap (5) carefully for cancel the air pressure.●Install brake across the rotor on bridge. Screwed bolt with the spanner.Note: Correct install process of the hexagon bolt.●Install brake pads and adjust clearance. Implemented section 3, notice theexplanation.●Cleaning the install flange on caliper and grease inside the pressure arm ballsocket before reinstall the brake chamber.●Install the brake chamber and screwed with spanner.Note: After the installation of brake chamber, the lowest chamber hole face theground must open, other mouths stop up.5.2. Screw dust cap replacementNote: If only replace the screw dust cap, does not need to remove the caliper andthe air chamber.Process:●Remove brake pad and push board according to section 3.●Push the caliper towards to brake chamber.●T ake off screw dust cap (10) from the ring groove on adjust screw (21).●T ake down from dust cap base with screwdriver.●Check screw thread.●Turning the adjust bolt for 30mm clockwise with the spanner.●Inspection thread corrosion and whether is damaged.●Turning it clockwise, feeling its lubrication and check the adjust screw thread.●Clean the base of caliper dust cap (10). (Arrow pointed)●Push new dust cap (10) on adjust screw. Install it on the base with kits. Observes itinstalls whether arrived.●Grease on the edge of dust cap (10) and install it on the base of adjust screw (21).Note: Guarantees the dust cap steadily in place and does not have the corrugation in the adjust screw ring groove.Installation process:●Install the brake pad and adjust the clearance (see Section 3).6. Rotor check/replacement6.1 Rotor check Check the rotor (Section 2.4) If the rotor reached the minimumthickness, it must be replaced.6.2 Rotor replacementNote: Generally recommend use new brake pad while install new/machined rotor.6.2.1 Uninstall the rotor:●R emove the brake pad. (see section 3)●T ake off the brake chamber. (see section 7)●T ake down brake from bridge. (see section 4)●T ake off the wheel and the rotor.(Refer to V ehicle Manufacture’srecommendations)6.2.2 Rotor installation:●I nstall the wheel and rotor. (refer to V ehicle Manufacture’s recommendations)●D egrease the rotor.●T urn the wheel and check the installed rotor (Section 2.4).●A djust ABS sensor refer to V ehicle Manufacture’s recommendations.●I nstall the brake (see Section 4).●I nsert pad (see Section 3).●I nstall brake chamber (see Section 7).7. Brake chamber replacementNote: Don’t use pipe wrench! Ensure your hands and fingers outside the caliperavoid hurts body!Note: Can only use the chamber assigned by the Vehicle Manufacture.7.1. Brake chamber removal:●Bleeds off the compressed air.●Remove the upper air pipe of brake chamber.●Remove the chamber from caliper.7.2. Brake chamber installation:Note: According to the brake installment position, only can open the scupperunderneath.●Cleans the sealing plane of the pressure are ball socket (arrow) and caliper beforethe brake chamber installation.●Screwed the chamber mounting nut alternately with spanner in torque ratingrequired by the air chamber supplier.●Connection the air pipe.Note: Never twist the braking line, place it originally avoid fiction with other sets.While exist air leak, finds the leakage and check the connection.●Function and performance examination.8. A djuster replacement8.1 A djuster removal●Remove brake pad (see Section 3).●Remove brake chamber (see Section 7).●T ake off brake (see Section 4).●T ake off upper bolt by hexagon wrench.●Remove adjuster and other parts in the caliper.Note: Don’t hurt the screw dust cap.8.2 A djuster installation●Grease inside the caliper.●Put the return spring (18) at each side.●Install the needle assembly and the adjuster.●Puts the washer and top head, screwed the bolt with spanner according to theopposite angle principle.Note: Guarantee the bolt tighted the moment of force.9. Troubleshooting11. List of mounting & maintaining toolsYOUFIN is in the process of logo replacement, new logo will put into practice gradually. It with the original logo is still the YOUFIN’s product. Final interpret right for the logo belongs to YOUFIN.。
