Repair of Rotac Actuators

Transcription

1 Repair of Rotac Actuators MP Model OVERHAUL INSTRUCTIONS Also Includes older styles RN CG XL HN Read the entire contents of these instructions before installing the actuator and before making any connections to the actuator. These instructions must be followed in all respects to avoid damage to the actuator and associated components and/or injury to personnel. For further information contact: Micromatic, LLC 535 Berne St. Berne, In Ph Fax of 11

2 Rotac TEARDOWN, INSPECTION AND ASSEMBLY PURPOSE: To instruct designated personnel in the teardown, inspection, seal replacement and the reassembly of Rotac Rotary Actuators. Minor repairs will be examined; however, repairs without proper engineering information and machine capabilities may be costly. These cases call for factory service and should be referred to the factory for repair. Factory repairs will bring the unit to the latest design within that product line. All workmanship and parts will carry a full warranty of 6 months usage, or 12 months from date of shipment, whichever comes first. TEARDOWN: 1. Clean exterior of unit as clean as possible. This will assure you that all substance found in the unit did not come from the exterior. This also makes it easier to disassemble in many cases. 2. Remove all burrs from shaft extension. 3. Match mark heads and body so that their relationship can be re-established when reassembled. 4. After removing head bolts from both heads, strike end of shaft with plastic mallet or aluminum bar stock, and allow the shaft to push the head off. Some newer units have threaded holes that will allow you to assist in separating the head from the body. DO NOT PRY HEADS OFF!!! Damage will occur to body or heads. 5. Pull the shaft out, being careful that the vane does not fall and nick the body. 6. The shoe will usually come out by pulling on it with your hands, however, it many sometimes be necessary to pull with your hand while tapping the dowel pins lightly. NEVER PRY THE SHOE OUT!!! 7. Remove all seals and inspect for cuts, nicks, or any other unusual conditions of the seal. (Compare to new seal kit). INSPECTION: 1. Examine oil residue inside actuator. This may give a clue as to why the damage has occurred. A. Dirty or gritty oil will cause scoring of internal surfaces. B. Varnish on internal parts can be a sign of oil in system running too hot. C. Corrosion or erosion of aluminum body. The use of 95-5 or similar high water based hydraulic fluid can cause corrosion or erosion of aluminum bodies, if electric current is running through the Rotac actuator. D. Metal particles - Metal chips can be found from valve spools, Rotac internal parts and other metal components in the system. The appearance of symptoms a, b, or d above, will require total flushing and cleaning of the entire system. Problems with aluminum bodies can be cured by totally grounding the machine electrically or cast iron bodies are available upon special request. 2. Wash all parts thoroughly and examine for defects. 2 of 11

3 A. Shaft (See Figure 1.) B. Body 1. Examine welded vane for cracks at "A" diameter, splines, keyways and any other area where stress may be applied. a. Spot-check by Magnaflux Three different materials needed and applied in order: SKC-S Cleaner SKL-HF/SKL-S Penetrant SKD-S Developer FOLLOW DIRECTIONS CAREFULLY ON BACK OF THE CAN b. Keyways or splines widened may fit loosely in coupling. This problem will only get worse and eventually cause shaft to break. Cause - poor fitting coupling. Too soft keys. c. Scoring on "A" (major) diameter. Any scratch.010 or more calls for terminal replacement. d. Scoring or galling on Figure 1- Shaft shaft journal. This problem can be repaired with hard chrome, however, many critical dimensions must be held - this type of repair must be performed by factory only. e. Scoring or galling on end of "A" (major) diameter. This is another problem that can be repaired; however, it is recommended that this type repair be performed by factory only. 1. Scoring of.010 or more calls for terminal replacement of this part. Any light scoring can be polished out with 400-grit emery cloth or it's equivalent. NOTE: When pressurized, the body will expand and contract. For this reason, plating or sleeving is not recommended by the factory for repair. 2. Cracks may be found across the dowel holes, bolt holes or ports. This calls for terminal replacement. 3. Dowel holes may be elongated or out of round. These holes may be drilled oversize or rebushed, however, the proper size and location of the dowel hole must be known to accomplish this repair. 3 of 11

4 C. Heads - 1. Bearing area units will have either, one or two separate bearings, depending on the model. a. Thrust bushing may be worn or scored on either the I.D. of the journal bearing area, the ID of the shoulder seal groove area of the bushing or on the face of the thrust surface itself. There are several styles of thrust bearings. One is a removable thrust bushing and one is part of the head (New Style for MP Model). See Figure 2. b. Replacement of bushing must be done in the following steps: Figure 2 MPJ HEAD i. Press out old bushings. ii. For the new style MPJ see Table 4 and MPR see Table 5. iii. Replace bushing seal (HN & XL style only). iv. Freeze new bushing to -100 degrees F. v. Press in with proper tonnage and insure bushing is firm against shoulder. vi. Bore bushing concentric with bolt circle dowels to proper size. vii. Regrind face of head so bushing thrust surface is true with head surface. viii. Cut shoulder seal groove in bushing concentric to bolt circle and dowel to proper dimension. (Step "viii" is not necessary for Model HN). ix. Recut head seal groove to proper depth. x. For models CG or MPJ composite bushing replacement requires boring of bushing concentric with dowel holes after installation. NOTE: MPR and RN styles of Rotac Actuators are assembled with needle bearings as well as a thrust bushing. Repeat steps i - ix above. The cage part of the needle bearing will require a light press fit. Lubricate the needle bearings and then place in inner race inside the needle bearing. 2. Oversize or elongated dowel holes Check both shoe dowels and body dowels a. Oversize or elongated shoe dowels may have been caused by the vane of the shaft contacting the shoe. Inspect the shaft at vane weld area for cracks and the shoe dowel holes for cracks. b. Oversize body dowel holes may be caused by racking and twisting Rotac. This may be a sign of over-pressurization or improper mounting. 3. Scoring on face of head. a. Improper filtration or gritty particles in the oil b. Side load on shaft. 4. Cracks in head are usually around bolt circle or dowel pattern. D. Shoes 1. Cracks across dowel holes or elongated dowel holes. This usually is caused by the vane of the shaft assembly coming into contact with the shoe. Inspect the weld on the vane of the shaft assembly for cracks. A shoe in this condition must be replaced. 2. Shoe seal wall cracked or chipped. This must be repaired. 4 of 11

5 E. Seals 1. Cut or shaved seal is usually done when assembled. This can occur in a number of different ways. Refer to assembly instruction for proper assembly. SEAL REPLACEMENT AND ASSEMBLY FOR MPJ-MPR-HN-XL-CG MODELS: The assembly area must be clean and free from all dirt, dust, or other harmful material. A Teflon or metal workbench is the best type bench for the assembly. Parts should be recleaned if necessary. A small pliable brush should be used so all seal grooves, dowel holes, bolt holes and other hard-to-get-at areas are clean. Remove all burrs that may be on any part. Do not break corners on shaft "A" diameter or body (see figure 1). These sharp edges are important to the operations and function of the Rotac actuator. Assembly tools are available for the following models: XL, CG, RN, and MP. If assembly tools are not available (see figure 3 and Table 1), use shim stock to protect the seals (see figure 6). For general seal location see figure 4 and figure 5. A. Lubricate all seals and internal parts with grease that is compatible with the driving fluid used. DE-ES lubriplate by Fiske Brothers is used at the factory. Petroleum jelly also works fine in most hydraulic systems. B. Shaft Seals 1. MPR-RN only place retainer seal, shaft seal and shaft seal back-ups or (shaft seal caps on later models built after January 1981) into retainers. Install retainers on head. Secure with bolts and torque to valve as shown in Table For Models MPJ and CG place shaft seal cushion and shaft seal cap into its respective groove. C. For models XL and HN place shaft seal and shaft seal back up into its respective groove. D. For CG only. Place ball in vertical drain hole of head. E. For CG only. Place spring on top of ball in vertical drain hole of head. F. For CG only. Place O-Ring seal (if replacement is needed) on groove of drain plug, then screw the drain plug assembly into threaded vertical drain hole of head, torque snugly, using 1/8 Allen wrench. FIGURE 3. Assembly Tools See Table1 for Parts listing G. MPJ-MPR-XL-CG. Place shoulder seal cushion into its groove. Be sure all entrapped air is out from under the cushion and seated in the groove. H. MPJ-MPR-XL-CG. Install shoulder seal with flat side against cushion I. Place head seal in its groove in the head. 5 of 11

6 J. Place shoe seal cushion in its groove around shoe. Place shoe seal cap on top of shoe seal cushion. This will only apply to model MPJ- MPR-CG-XL-RN and HN models 3-2, 3-4 and 6-3. If the shoe seal groove width is the same as the shoe seal, no shoe seal backup spacers will be required. If the groove is wider than the seal, the seal kit provides back up spacers to fill the groove. K. For Models HN 3-6, 6-6, 10-5, 10-8 and the shoe seal is installed in its groove and 1 shoe seal backup is installed on each side of the shoe seal. L. Place dowel pins in shoe. M. Place vane seal in its groove around vane. Figure 4. MPJ Seal Reference Place vane seal cap on top of vane seal cushion. This will only apply to model MPJ-MPR-CG-XL-RN and HN models 3-2, 3-4 and 6-3. If the vane seal groove width is the same as the vane seal, no vane seal backup spacers will be required. If the groove is wider than the seal, the seal kit provides backup spacers to fill the groove. N. For models HN 3-6, 6-6, 10-5, 10-8 and the vane seal is installed in its groove and 1 vane seal backup is installed on each side of the vane seal. O. Insert dowel pins into body. P. Place one head on body. Match the marks made on the body and head when actuator was disassembled. Q. Secure with screws and torque to valve shown on chart found in Table 2. R. Install shoe into body. Leave approximately 1/4 inch between end of shoe and head. Double vane actuators require two shoes and only one shoe should be placed in the actuator at this time. S. Grease the ID of the body, shaft "A" diameter shoe surface to allow the shaft to slide into the actuator with ease. See Figure 3. Figure 5. MPR Seal Reference T. Place the vane of the shaft at right angles to the shoe. Tuck the shoe seal and the vane seal into the body and push straight in until the vane is approximately 1/8 inch from the head. While the shaft is being inserted into the body, pressure must be applied to the top of the vane seal to prevent the seal from riding upward. U. Install the second shoe (if required). Remember to leave the shoe about 1/8 inch higher than the shaft. V. Push the shaft and shoe(s) down together with the shaft bottoming first. CAUTION: If the shoe bottoms first, the sharp edges of the shaft will pinch the corners of the shoe seal and cause unusual high internal leakage. W. Press the corners of the shoe and vane seals below the surface of the body. 6 of 11

7 X. Install the remaining head. Y. Pull down evenly and secure with screws. Z. Torque to valve shown on chart on Table 2. Factory built Rotac actuators are then tested for internal by-pass leakage and breakaway pressure. See chart on Table 3. FIGURE 6. Shoe and Shaft Installation Note: Install shoe into body with shaft in the approximate location as shown, Position #1 (adjacent to the shoe). Caution: DO NOT ALLOW VANE SEALS TO CROSS SHOE DOWELS HOLES OR PORT HOLES. After shoe and shaft are installed, rotate shaft to Position #2 (Vane Seal approximately opposite the shoe). Table 1. Assembly Tool Kits for All MP Models Will fit most RN/XL/CG units Includes both the Shoe Seal Protector and the Shaft Vane Seal Protector Model Size MP 3-2, 3-4 MP 6-3 MP 8-4 MP 10-5 MP 11-6 MP 12-8 Part Number GT-3239 GT-3240 GT-3241 GT-3242 GT-3243 GT of 11

8 TABLE 2. TORQUE CHART Rotac Models MP-CG-RN-XL-HN UNIT STYLE SIZE BOLT SIZE TORQUE MP in. Lbs. MP in. Lbs. MP-RN-CG-XL 32 3/ Ft. Lbs. MP-RN-CG-XL 34 3/ Ft. Lbs. MP-RN-CG-XL 63 1/ Ft. Lbs. Cast Iron/ Aluminum MP-RN-CG-XL 84 1/ Ft. Lbs. MP-RN-CG-XL 105 5/ Ft. Lbs. MP-CG-XL 116 3/ Ft. Lbs. MP-CG-XL 128 7/ Ft. Lbs. HN 32 5/ Ft. Lbs. HN 34 5/ Ft. Lbs. HN 36 5/ Ft. Lbs. HN 63 1/ Ft. Lbs. HN 66 1/ Ft. Lbs. HN 105 5/ Ft. Lbs. HN 108 5/ Ft. Lbs. HN / Ft. Lbs. TABLE 3. BREAKAWAY & LEAKAGE CHART Rotac Models MP-CG-RN-XL-HN INTERNAL BY-PASS LEAKAGE: Leakage checks to be made at a gauge pressure of psi listed. Air pressure to be maintained at psi listed for one (1) full minute before check is started. BREAKAWAY PRESSURE: Rotation of a Rotac actuator output shaft must be accomplished by an internal pressure not in excess of psi listed. This applies to both single and double end units. Oil Medium Pneumatic Medium Max. Breakaway Maximum Leakage per 1000 Cu. In. PSI. Maximum Breakaway Maximum Leakage Cu. Ft. per PSI MODEL SIZE in PSI 1V 2V in PSI 1V 2V HN HN HN ** HN HN HN HN HN MP-CG-RN-XL MP-CG-RN-XL MP-CG-RN-XL MP-CG-RN-XL MP-CG-RN-XL MPJ-CG-XL MPJ-CG-XL **600 psi maximum of 11

9 TABLE 4 Bearing Replacement Chart for the NEW STYLE MPJ Rotac Models UNIT STYLE HEAD A B C D E F G AS MPJ 3-2, MPJ MPJ MPJ MPJ MPJ of 11

10 TABLE 5 Bearing Replacement Chart for the NEW STYLE MPR Rotac Models UNIT STYLE HEAD B C D F G S MPR 3-2, MPR MPR MPR of 11

11 Reference 11 of 11