Routine Care and Maintenance for Crane II

1.       Propeller Shaft

The curvature of the shaft should not exceed 1/2000*1（1 represents the effective length of the shaft）, And the shafts should be aligned and replaced if the curvature exceed the value, especially the high speed shaft vibration will appear when the curvature is too big. But the curvature of low-speed shaft is allowed to exceed 1/1000*1（1 represents the effective length of the shaft）or the shaft should be replaced only when the curvature exceeds 1mm.

2.       Bearing

The bearing should be kept in lubrication state. Before re-oil, the bearing shall be cleaned with petrol. And the oil amount should be 2/3 of the cavity of bearing. Under normal circumstances, the elevated temperature shall not exceed 60℃-70℃, and the sound of bearing shall be even. The bearing must be inspected when the temperature is too high and the noise is too big and should be replaced when feather wear, point corrosion or crackle are found on the inner or outer ring raceway or on the surface of ball(column) or the diametral clearance of bearing increases to 0.2mm.

3.       Brake Wheel

There should be no deficiency or greasy dirty on the braking friction surface of the brake wheel. The brake wheel should be discarded as useless when attrition exceeds 5mm or there is groove deeper than 4mm worn on the surface.

Brakes whose keyways (exclude rolling key) are widened due to improper usage is allowed to be continuously used by staggering 120° at the original keyway position and inserting a keyway once. But the radial runout of the installed brake wheel should not exceed the regulations in the following table

Diameter of Brake Wheel		<50~120	<120~250	<250~500	<500~800
Run-out	Radial	0.08	0.1	0.12	0.15
	Head face	0.15	0.2	0.25	0.3

4.       Lifting Hook

6.1 Scrapping standards

When one of the following situations occurs, the lifting hook should be discarded:

a)      Crackle.

b)      The attrition of the critical section reaches10% of the original size.

c)      The opening size increases by 15% as compared with the original sized.

d)      The torsional deflection exceeds 10°.

e)      Plastic deformation is found on the critical section or hook neck.

f)       When plate hook bushing is worn by 50% of the original size, the bushing should be discarded.

g)      When the plate hook arbor is worn by 5% of the original size, the arbor should be discarded.

6.2 When 10% of the rivets of the plate hook loose, the rivets should be replaced.

6.3 Protection

h)      Strictly forbid to make repair welding on the hook;

i)       The nut of lifting hook and the screw joint should be inspected at least once every year. They should be replaced immediately when there is corrosion and blister;     

j)       Protection covers should be added on the lifting hooks used for water explosion blast cleaning or used in other corrosion occasions to avoid corrosive substance eroding lifting hook handle and lifting hook nuts and so on.

5.       Pulley

1.1  Scrapping Standards

When one of the following situations occurs, the pulley should be discarded:

k)      Crackle

l)       Uneven wear of groove reaches 3mm

m)    The wall thickness of the groove is worn by 20% of the original thickness.

n)      The diameter of the groove bottom is worn by 50% of the diameter of steel wire rope.

o)      Other deficiency damaging the steel wire rope.

1.2  Protection

p)      Inspect the lubricating situation of the pulley block regularly and ensure its flexible rotation.

q)      Strictly forbid to be hung inclined or crooked because it is the main reason for the premature failure of pulley.

2.      Wheel

2.1  Scrapping standards

When one of the following situations occurs, the wheel should be discarded:

a)      Crackle.

b)      The wheel flange is worn by 50% of the original thickness

c)      The bending deflection of the wheel flange reaches 20% of the original thickness.

d)      The wheel thread is worn by 15% of the original thickness;

e)      When the running speed is lower than 50rn/min and the out-of-roundness reach I mm; when the running speed is higher than 50rn/min and the out-of-roundness reach 0.5mm.

2.2  Protection

Eliminate the gnaw rail, slippage or triangle leg in time

2.3  Replacement

After installation, the new wheel set should meet the requirements for the installation of wheel set in the "V. Installation and Commissioning" of this instruction manual. Meanwhile, should ensure the flexible rotation of the wheel set.

3.      Coupling

3.1  Scrapping standards

f)       Crackle, broken perforation is found on the gear coupling or the gear is worn by of the original thickness.

g)      The elastomer ageing occurs on the spring coupling or the diameter of the coupling has reduced by 2mm.

h)      The shaft sleeve on the universal joint crucifix is worn and increases by 5% of the original bore diameter or the spline is worn by 15% of the original gear thickness.

3.2  Protection

Mainly check whether the lubrication and seal is good or the axial displacement is within the required scope.

4.      Winding Drum Group

4.1  Scrapping standards

When the crackle found on the winding drum or the drum wall is worn by 20% of the original thickness, the winding drum should be discarded.

4.2  Protection

a)      Inspect the arrangement of the steel wire rope on the winding drum regularly; problems should be solved immediately after found.

b)      Put lubricating oil on the steel wire rope regularly to avoid dry friction between winding drum and steel wire rope;

c)      The inner gear disc should be cleaned thoroughly every time overhaul, adequate lubricating oil should be filled when assembly.

d)      For the winding drum with four-rope grab, when replace the hoisting drum, the open and close drum must be replaced. But the open and close drum allowed to be replaced only。

5.      Rail

a)      The crane track and trolley track should be inspected at least twice one year;

b)      Whether the fixation of transition to production is good, the welded joint of the welding pressure plate dehisces, the nut of bolt pressure plate losses and the track is kept close to upper cover plate of main beam and track-bearing beam;

c)      Details of the installation and adjustment of the track see the requirements in the “Installation and Commissioning” of this instruction manual.

d)      When replace the track, using oxy-acetylene flame to cut track pressure plate is not permitted;

e)      When welding, it is not allowed to strike fire on the track;

f)       Oil dirty is forbidden to be adhere to the track thread.

6.      Brake

6.1  Inspection

The brake of the hoisting mechanism should be inspected every shift and that of running mechanism should be inspected at least once every two or three days. When inspect, special attention should be paid to the following matters: all parts of brake system should act preparedly, the bolt cannot be jammed. The brake shoe should integrate closely with the brake wheel correctly and the packing material of the brake shoe should be good When the brake shoe opens, the clearance between the brake shoe and two sides of the brake wheel should be everywhere equidistant.

Switch the current on to check the opening condition of the brake shoe, if found out of order, should further check whether the matching pusher is working normally.

Inspect the brake torque, the brake of hoisting mechanism must support 1.25 times of rated load lifting capacity reliably. The brake of running mechanism should be able to stop the cart and trolley, but it inadvisable to be adjusted over tight to avoid severe slippage of wheel or causing vibration and shock.

The packing material of the brake shoe should be replaced when it is worn by more than 50%. The surface of the brake wheel should be smooth. Clear the dirt up regularly with kerosene wiper.

6.2  Adjustment

If the brake wheel gives smoke or burning smell off when it runs, it means that the temperature of brake shoe and brake wheel is too high (the temperature should not exceed 200°C), and at this time, should adjust the clearances between brake shoe and brake wheel and make them equivalent.

Current general-purpose overhead crane always uses YWZ type electro­hydraulic double-shoe brake and DC electromagnetic brake, and their installation and usage can see the instruction manual of supporting manufacture

7.      Reducer and Gear Pair

Gear wear: it includes running-in wear and abrasive wear. For the former, mainly improve the smooth finish of the gear surface; for the later, improve the method for removing the bank sand, metal filings and other mechanical admixture in the lubricating oil（grease). The gear wear is the main destruction form of the exposed gear. Protective cover should be added on the gear to avoid dust falling into. The limit of allowance for wear is generally 10% of the original gear thickness (heavy, super heavy hoisting mechanism) or 16% (intermediate, light mechanism and open and close mechanism) or 25% (other mechanisms).

Gear pitting: this is the most common destruction form. The gear should be replaced immediately when the pitting area exceeds 30% of the whole working area of the gear and the pitting depth exceeds 10% of the gear thickness.

Gear gluing: the main reason is caused by the lubricating oil not forming continuous oil film. To avoid gluing, must use industrial gear oil No.SO (in winter) or No.100, 120 (in summer); using another engine oil is not permitted. The oil amount should be added according the scribed line on the inventory probe. Sometimes, because the cone bearing does not bear tight and the axial float is too large, it will cause gear surface local contact and gluing. The gluing should be eliminated aiming at malpractice. The glued gears should not be reused and should be replaced.

Plastic deformation on the surface of gear: under the low-speed over load condition, this will easily occur on the gear surface. The strip edge should be filed smooth to improve the viscosity of lubricating oil or change gear. When replace the gear, should appropriately raise the hardness of the gear surface.

Gear fracture: gear fracture mainly occur on the hardened gear, including overload breakage and fatigue fracture. For the former, mainly prevent sudden overload, and for the later, frequently check whether there is crackle on the gear root. The gear should be replaced immediately after the crackle is found.

Noise and impact sound: mainly contingent on the machining precision and assembling accuracy. When overhaul or replace, close type reducer should not less than grade 887 stipulated in the GB I 0095, the exposed gear should not less than grade998.     After assemble, make it run idle when the oil has not be added, and make following observation and judgments:

a)      The contact zone is generally around the pitch circle. When the gear length direction must reach 60% (close type) or 50% (expose type), or gear height has not reached 45% (close type) or 40% (expose type), but one or two even lines have formed, it should be regarded appropriate and will reach upper value after load running.

b)      There is discontinuous but ringing impact sound. It is mainly because there is a scar on a certain gear; it merely needs to be rounded off with fine file or oil stone after it is found out.

c)      The noise is loud but even. It is mainly because the gear top gnaws the gear root. It merely needs to abate sharp comer of gear top with fine file.

d)      There is uneven noise, mainly because the gear bevel angle is not straight or assembling is crooked, which is not easy to repair. Old gears should be discarded and new ones should be changed. When use cone bearing and the conical surface is not bear tight, this will be also occurred. At this time, it merely needs to bear tight with adjusting crew.

Oil leakage in reducer: when the connecting bolt, oil drain plug and oil sight cap bolt on the upper and lower shell of the reducer are not screwed up and the sealant loses efficacy, may cause lubricating oil leakage. It can be improved or solved by taking the following measures:

a)      Replace the deactivated leather packing and ring, and fast the bolt on all parts of the reducer.

b)      Recast the sealant. Shuck off the deactivated sealant on the mating face and tile lid. Or clean them with acetone, ethanol, or ethyloleate and petrol, each of them accounting for 50%, and then dry them by airing and coat sealant on them evenly.

Assemble mould after 3-5 minutes (For non-drying bonded sealant, we can wait longer). Screw au bolts down and tighten them again after about 24 hours. Then it can be put into operation.