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Các vòng bi chống ma sát thường được ép hoặc thu hẹp trên trục và thiết bị kéo phải được sử dụng để loại bỏ chúng. Kéo kẹp (pulling jaws) hoặc ngón tay kéo phải nằm phía sau của bên trong ổ lăn. Khi các bộ phận khác trên một trục không gây trở ngại bạc ổ trục có thể được hỗ trợ bởi một vòng chia và trục ép ra bằng cách sử dụng một máy ép đứng.
SECTION Ⅵ – PHẦN VI MAINTENANCE – BẢO TRÌ 6.5 CASING GASKET INSTALLATION – LẮP ĐẶT VỎ GASKET (VÒNG ĐỆM) In general, new gaskets should be installed in the pump after the pump has been dismantled The gaskets should be of the same material and thickness as the original gasket so it will compress to the same thickness Nói chung, vòng đệm nên lắp đặt bơm sau bơm tháo rời Các miếng đệm nên có vật liệu độ dày gioăng ban đầu để nén đến độ dày tương tự 6.６ MAINTENANCE OF WEARING RINGS All pumps come equipped with renewable wearing rings as standard construction Generally it is recommended that the rings be renewed when the original clearance has doubled The renewal of the wearing rings will depend upon required pump performance since capacity will fall off as the radial clearance at the running joint increases due to wear 6.７ MAINTENANCE OF SHAFT AND SHAFT SLEEVE When the pump is dismantled, examine the shaft carefully Its condition should be checked at the impeller hub fit, under the shaft sleeve and at the bearings The shaft may become damaged by corrosion, due to leakage along the shaft, at the impeller or shaft sleeve Anti-friction bearings improperly fitted to the pump shaft will result in the inner race rotation on the shaft , thus causing undue damage Check the shaft keyway for distortion Check the shaft runout at the impeller and coupling seat with a dial indicator by supporting the shaft journals on “V”blocks or rollers Replace a shaft that is bent or distorted ( maximum 0.05 ㎜ ) 6.8 MAINTENANCE OF BEARINGS Anti-friction bearings are usually pressed or shrunk on the shaft and a pulling device must be used to remove them The pulling jaws or fingers must be located behind the shoulder of the inner race When other parts on a shaft not interfere the bearing may be supported by a split ring and the shaft pressed out using an arbor press NOTE : Unless extreme care is used when removing an anti-friction bearing, the bearing may be damaged to the extent that it is no longer useable Always check the bearing immediately after removal for any imperfections or any play between the races It is recommended that new bearings be used for replacement of removed bearings sine very often damage caused by removal cannot be detected until the pump is put into operation When mounting antifriction bearings on the pump shaft remember that the satisfactory operation of anti-friction bearings requires that the inner race be firmly held on the shaft so that it cannot turn on the shaft It also is important the fit of the outer race prevent its free rotation in the housing There are two methods in use for mounting a bearing on a pump shaft : Heating the bearing to expand the inner race and shrinking it on the shaft Forcing the bearing onto the shaft The first method is referred Heat the bearing in an oil bath or electric oven to a uniform temperature of 80 － 120℃ When heated, quickly mount it on the shaft If the alternate method is used, apply the force by means of an arbor press or hammer blows If an arbor press is available, use a tubular sleeve, a ring, or small blocks of equal thickness to apply the force to the inner race With a proper care it is possible to drive a bearing onto a shaft by hammering on the center of a block of metal or wood mounted on top of a tubular sleeve held against the inner race In forcing a bearing onto a shaft be careful that the race is never cocked Check the position of the bearing on the shaft shoulder MAINTENANCE OF IMPELLER Slightly eroded parts can be repaired by welding Dynamically balance impellers after any machine work 6.10 BEARING BRACKET Thoroughly flush and clean the oil passages Remove all scale and deposit in the water circulation space by scraping and chemical treatment when necessary 6.11 MECHANICAL SEAL OR PACKINGS Mechanical seal is a precision device Extreme care is required for the maintenance of mechanical seal For detail , please refer to the mechanical seal instruction book (For packed pumps) The type of packing used will be governed by the particular service The following procedure should be followed in repacking a stuffing box : Loosen the stuffing box gland Slide the flange back over the gland bushing halves and remove the bushing Remove the old packing with a packing puller and clean the stuffing box Make sure the packing is of the correct type and size Packing should be cut long enough ( approximately 1.6 longer ) to insure that the O D of the packing ring hugs the stuffing box rather than the sleeve Insert each ring of packing separately, pushing it as far as possible into the stuffing box seating it firmly Stagger the rings so that the joints are 90 deg or 180 deg apart After insertion the required number of rings of packing the seal cage can be inserted Make sure the seal cage is located directly under the sealing connection and that the insertion of successive rings will not displace it Continue adding the required number of packing rings Install the gland and tighten the gland nuts by hand ; then back off the nuts until the gland is loose In tightening the gland the nuts should be brought up uniformly so that the gland will not be cocked and so that the packing is subjected to uniform pressure New packing has to be run in It is good practice to start the pump with the stuffing box gland quite loose After the pump has been running for approximately 10 to 15 minutes, gradually tighten the stuffing box gland until leakage is reduced to a constant drip Packing that is too tight in the box will cause undue friction, creating heat which will glaze the packing and possibly score the shaft sleeves Packing must remain soft and pliable Precaution : it may be impossible to and the last ring of packing in the stuffing box and still insert the gland When this occasion arises, omit the last ring of packing and tighten the gland Continue to tighten the gland daily, allowing for proper leakage, until the packing has seated itself well enough to allow the final ring to be inserted 6.12 THROAT BUSHING The clearance between the throat bushing and shaft sleeve will not increase under normal operation Do not renew or refit this bushing until it is necessary 6.13 PERFORMANCE TEST When the installation is new, a test run of the pump should be conducted with calibrated gauges to determine system head values for known capacities to provide information for use in checking performance as wear takes place This data will prove invaluable in determining maintenance schedules and in selecting spare parts to be kept on hand at a later date