Viking 855 service manual Pump Rotation

Do not attempt to reuse a PTFE (derivative) encapsulated O-ring if it has been removed. Immerse a new O-ring in boiling water for a few minutes. Remove it from the water and stretch out the O-ring so it will fit onto the casing hub without forcing it over a sharp edge. Run hot water* over the O-ring until it shrinks down tight onto the pilot of the pump. Dry with compressed air.

2.Clean the rotor and shaft so it is free of dirt, grit and other debris and apply lubricant. Place one thrust washer onto shaft so that the blind hole in thrust washer will line up with the drive pin on the back of the rotor. Push the rotor and shaft it into the casing as far as it will go.

3.Slide the second thrust washer onto the shaft, drive hole facing out and then install the key into the shaft.

4.Slide the inner magnet onto the shaft and engage the pin of the magnet into the hole of the thrust washer. Install the locknut, beveled edge out. Tighten the locknut to the torque value given in Table 6. Place a mark on the trailing edge of the locknut slot. Refer to Figure 16. Back off the locknut until the leading edge of that same slot lines up with the mark. This will establish the proper clearance for the thrust washers.

5.Place the set collar on the locknut and install the two machine screws.

6.If the old metal shims are not reusable or if any parts have been replaced, operating clearances will need to be re-established. Refer to “ADJUSTING END CLEARANCE” on page 13. Otherwise, place the head shims on the head. The proper amount of shims should be used to provide the correct end clearance. Table 7 gives the quantity of shims available in a gasket set along with standard end clearance.

	NORMAL1
	END	SET OF HEAD
	CLEARANCE	SHIMS INCLUDES
	(inch)
AS, AK, AL 855	0.005	(1) .007
		(1) .005
KE, KKE 855	0.005	(2) .002
		(2) .001

1End Clearances are adequate for viscosities up to 2500 SSU /

540cSt (SAE 40 lube oil at room temperature). Higher viscosities require additional clearances. As a general rule the end clearance is doubled for higher viscosities. For specific recommendations for end clearance for viscosity or for operating temperatures above

225°F (107 °C), check with your Viking representative or consult the factory.

Table 7

7.Coat the idler pin with a suitable lubricant and place the idler on the idler pin in head. Make sure the O-ring for the head is installed (In the O-ring is PTFE, follow instructions given in step 1).

8.The head can now be assembled onto the pump. Tilt the top of the pump head away from the pump slightly until the crescent enters the inside diameter of the rotor and rotate the idler until its teeth mesh with the rotor teeth.

The pump head and casing should have been marked before disassembly to insure proper reassembly. If not, be sure the idler pin, which is offset in the pump head, is placed in the 12 o’clock position from the port connections to allow for proper flow of liquid through the pump. Install the head capscrews. Rotate the shaft to make sure it turns freely.

9.Follow the instructions listed for assembling the appropriate size coupling on page 12.

Locknut Torque Requirement

	In-Lbs	N-m
MD2-B	60	6.8
MD2-C	80	9

table 6

PUMP ROTATION

The pump is designed to operate in either direction. Process fluid is generally fed to the inner thrust washer and bushing interface and then through a groove in the bushing to the outer thrust washer. Then the fluid is pulled into the canister bushing and back through the hollow shaft and idler pin to the suction side of the pump. When the pump is operated in the opposite direction, the fluid flow is reversed.

Mark

Leading Edge of

Locknut

figure 16

*Hot water makes the PTFE more pliable and allows the inner elastomer to pull the PTFE back to the orginal size.

figure 17

SECTION TSM 685.2 ISSUE C PAGE 11 OF 16