Pompetravaini MCU Series, Disassembly & Assembly Instructions, Page: 4 / 20

Disassembly & assembly instructions single stage centrifugal pumps
TC… - MCU-… 4
2.2 - ASSEMBLY
Visually and dimensionally examine the components to be replaced. Verify the integrity of the component and quantify
the degree of wear (for the main dimensions see tab. 2 - 3 - 4 - 6 of chapter 10). When new parts are required always
insist on original parts from POMPETRAVAINI.
In case of doubts or should there be any questions regarding the above, do not hesitate to contact POMPETRAVAINI or
the nearest authorised representative.
To replace the wear ring VDMA 502 it is required to loosen the set screws VDMA 904, using a puller or in the event of
difficulty the wear ring can be machined on a lathe.
Pumps with open impeller (series TCA and MCU-CHA) must have the proper clearance between the wear plates and
the impeller (contact the factory for specific values).
It is good practice to replace all gaskets and packing rings (even if they do not show evidence of defects), bearings and
mechanical seals that show wear grooves and excessive tolerances.
Clean each components using suitable cleaning agents and compatible with the materials of construction. Bearings
must be decreased with a solvent such as Naphtha, allow them to dry and then lubricate with oil. To help with the
bearing installation it is recommended to pre-heat the bearings to approximately 80
0
C.
If there are no complications and the components do not show any defects, wear and scratches on the sealing faces,
the assembly steps will be by proceeding the reverse of the disassembly.
Fitting of mechanical seals or packing rings are described in chapters 5 or 6. See chapter 10, tab. 2 - 3 - 4, for
dimensions details.
During assembly the fitting of the various components must be free of interference and damages.
For a positive placement of the gaskets it is suggested to use a compatible fluid (example oil) to help keeping the
gaskets in the sealing area.
See fig. 17 of chapter 10 for torque values of bolts and screws.
After the assembly it is suggested to hydrotest the pump for leakage. The test pressure should be at least 1.2 times the
maximum working pressure ma not less than 4 bar. The seal chamber of pumps fitted with double back to back
mechanical seals, should also be pressurised.
3 - DISASSEMBLY AND ASSEMBLY OF PUMPS SERIES
MCU-CH group 3 NS and 4 NS
3.1 - DISASSEMBLY
(See the section drawings of fig. 12 - 13 - 14 of chapter 8).
Drain the oil from the bearing frame by removing the drain plug VDMA 903.4.
Remove the bolts from the studs VDMA 902.2 so that the rotor may be removed from the pump.
Place the rotor assembly in the vertical position with the drive end toward the bottom.
Loosen the impeller nut VDMA 925 and remove the impeller VDMA 230 from the shaft VDMA 210. Remove the bolts
VDMA 914 and remove cover VDMA 471.1 (pay attention to the stationary seal element that is left in the cover, for back
to back double seal arrangement).
Remove the shaft sleeve VDMA 524 with the seal rotating element still on the sleeve together with the locating ring
VDMA 485. If the locating ring requires replacement be sure to mark its location prior to removal.
For pumps with packed stuffing box it is required to remove the nuts from studs VDMA 902.3, remove the seal gland
VDMA 452 attached to the cooling cover VDMA 165 and finally remove the packing rings VDMA 461.
Removal of mechanical seal(s) and of packing should be carried out carefully to prevent damaging any of the various
components. Remove the cover VDMA 161 and the mechanical seal cover VDMA 471 or the seal gland VDMA 452. The
seal stationary element is still in the seal cover, remove it if replacement is required.
For “CARTRIDGE” type mechanical seal insert the seal spacers prior to removal of the seal. The seal spacers will block
the seal with its sleeve, loosen then the set screws that lock seal sleeve to the pump shaft, remove the nuts from the
studs that attach the seal flange to the pump and slide the Seal Cartridge out.
To completely disassemble the bearing frame proceed as described below.
Remove the splash ring VDMA 507. With a gear puller remove the half coupling from the pump shaft and the key VDMA
940. Remove the screws VDMA 901.2, remove the casing cover VDMA 163 together with the outer ring of the roller
bearing VDMA 323. In the event the outer ring of the roller bearing requires replacement, it is necessary to remove the
snap ring VDMA 932.3 and then utilise the external extraction holes.
Rotate the bearing frame with the drive shaft end upward, remove screws VDMA 901 and bearing cover VDMA 360.2.
Remove the shaft VDMA 210 with bearings VDMA 320. To replace these bearings remove first the bearing nut VDMA
923.
3.2 - ASSEMBLY
Assembly procedures are same as given under paragraph 2.2 (for components type and dimensions see tab. 5 of
chapter 10).