Multitech 1777.8/7-10 G3 operating instructions Multitec, Radial bearing

Multitec

Radial bearing

Versions C and D are equipped with a deep-groove ball bearing as radial bearing. (The other versions are fitted with a plain bearing in the suction casing). The outer race of the deep-groove ball bearing must have axial play. The bearing is installed without spacer discs 551.1.

Fig. 42

7.4.4.1 Temperature of the rolling element bearings

Caution	The temperature of the rolling element bearings,
	which run at 3000 1/min and more, can be 90￿C.

Manual temperature checks are not sufficient !

-The bearings only reach their normal operating temperature after several hours of operation.

-When a new pump is started up, the bearing temperature may exceed 95￿C. After 2 or 3 operating hours it will sink slowly and level out to a constant value after approx. 1 week.

-A temperature rise may occur after service activities

comprising replacement of the bearings or dismantling of the hydraulic system.

Should the temperature exceed 100￿C during start-up, switch off the pump and perform the following checks:

-Check whether the unit is correctly aligned.

-Remove the bearings, check grease quantity. Excessive amounts of grease will cause increased temperatures.

-Verify bearing type and arrangement (see 7.4.4.4)

-Re-start the pump. Ensure tight press fit between outer races and cover (fixed bearing).

7.5Re-adjusting the clearance gaps

7.5.1Maximum clearance gaps

The following max. clearances on the gap diameter apply:

D

Impellers 230 and 231
Suction side clearance gap	0.8 mm
Clearance gap at the hub	0.8 mm
Balance drum 59-4	0.8 mm
Suction casing 106.1 and	1.0 mm if the fluid is pumped
spacer sleeve 525.2 (C and D	from a vessel under vacuum
versions only)	conditions
	2.5 mm for all other operating
	conditions

Should wider clearances be found, the parts subject to wear must be replaced.

Note: Pump performance is adversely affected by excessive clearances. Losses in efficiency and discharge head will occur.

7.5.2Repairs

Clearance between impeller 231 and suction casing: Sizes 32 to 65 for material codes 10,11, 12, 13:

Re-working the suction casing and mounting a spare casing wear ring as per ZN 1095 and re-working the impeller.

For other pump sizes and material codes:

Replacing the casing wear ring 502.1 with a spare ring as per ZN 1095 and re-working the impeller.

Clearance between impeller 230 and disc 550.1 or casing wear ring 502.2

(Sizes 125 and 150):

Replacing the casing wear ring 502.2 with a spare ring as per ZN 1095 and re-working the impeller.

(Sizes 32 to 100):

Two repair methods are possible:

a)Replacing the impellers 230 and discs 550.1 by new ones. Quick repair method, no re-work of parts required.

b)Re-working the impellers 230 at the impeller eye by deposit welding and subsequently machining to the original diameter. This repair method is used for impellers made of stainless steel.

Clearance gaps between impeller 230 and diffuser:

a)Re-working the impellers at the sealing gaps of the hubs. Re-working the diffusers and installing an interstage bush as per ZN 140.

b)Should hub thickness be insufficient after re-working, replace the impeller or fit a spacer sleeve (see drawing below). The spacer sleeve must be driven by the impeller key. Make sure that the load-carrying key length in the impeller is at least 2/3 of the total (load-carrying) key length.

Fig. 43

Installation and returning to service

Please refer to the appropriate sections of these operating instructions.

25