INTRODUCTION
This service bulletin explains how to remove,
replace and lubricate the Besser Slump Mixer's Air/Grease Purged Dust Hubs. The
function of the dust hubs is to prevent leakage of the slurry.
IMPORTANT: For the dust hubs to function
properly the following four steps have to be taken:
- The dust hub assembly must be properly
assembled on the shaft.
- Grease must be continuously supplied
to the seals.
- Air must be continuously supplied to
pressurize the seals.
- The dust hub halves (G) must be smooth
and aligned in order to provide the seals with a proper seating. Worn
dust hubs should be replaced.
SAFETY
Follow standard safety procedures when working on
the mixer including the safety procedures noted in the
mixer catalog. Stay clear of the mixer until the mixer is off,
the main panel is locked out and all mixer
component's motions are stopped. Before the mixer is
operated, properly close and secure the front panel and make sure
all guards and safety devices are properly installed.
PARTS ASSEMBLIES
The following part numbers are the replacement dust
hub assemblies for Besser mixers:
No. 619029 Dust Hub Assembly. (SM-6)
No. 619030 Dust Hub Assembly. (SM-9 & SM-10)
Fig. 1 Removing the Dust
Hub Assembly
STEP 1
EXAMINE NEW PARTS
- Do you have all of the proper parts?
- Are the parts free from damage and burrs?
- Do the dust hub halves (G) align properly on
the inside and outside diameters?
STEP 2
REMOVING THE DUST HUB ASSEMBLY
Remove the old dust hub in the following manner:
- Remove collar assembly A.
- Remove seal retainer B.
- Remove seal housing C.
- Remove dust hub retainer plate D.
- Remove seals E1 and E2 and spacer plate
F.
- Remove dust hub G.
STEP 3
PREPARATION FOR INSTALLATION
Check the following:
- Are the old parts you plan to reuse free from
damage, burrs and wear?
- When the seal housing halves (C) are bolted together,
they must be aligned on the inside diameter at the seams.
If they are misaligned, a new housing must be ordered.
- Clean the mixer head area where the seal housing
(C) and dust hub retainer plate (D) bolt on. Clean the
blade shaft area where the dust hub (G) bolts on. Clean
collar assembly (A), seal housing (C) and seal retainer (B).
Fig. 2 Installing the Dust Hub Assembly
STEP 4
INSTALLING THE DUST HUB ASSEMBLY
-
Install dust hub retainer plate A.
-
Place half of dust hub B on the blade shaft and
over the locator set screw J.
-
Place the other half of dust hub B on the blade
shaft and bolt the dust hub halves together loosely.
-
Slide dust hub B along the blade shaft and
into position against dust hub retainer plate A. Secure
dust hub B to the blade shaft. Make sure the dust hub
halves are aligned on the outside diameter at the seams.
Misalignment will cause excess seal wear.
-
By manually turning the drive pulley, position the
blade shaft in its center location. The center location of
the blade shaft is the midpoint between any side-to-side and up-and-down blade shaft movement.
-
Install seal housing C by placing the halves
around the blade shaft and bolting the top half to the lower
half (the top half of the seal housing is the half with
two threaded holes for the air and grease fittings).
Seal housing C must be centered so that the space
between the housing and dust hub B is equal all the way around
within 1/64th inch.
-
Secure seal housing C and dust hub
retainer plate A to the mixer head.
-
Pack grease between seal housing C and dust hub B.
-
Pack grease into the inner cavity of seals
D1 and D2.
-
Install seal D1 on the blade shaft so that the
seal's cavity is pointed towards the mixer head and the
seal's split is in an upward position. Move the seal up into
the seal housing, making sure that grease fills the
space between the seal and the seal housing.
-
Install spacer plate E on the blade shaft. Keep
the spacer plate's chamfer edge towards the mixer's head
and position the split line of the halves in a
horizontal position. Make sure the halves do not overlap.
-
Fill the spacer plate cavity with grease.
-
Install seal D2 on the blade shaft so that the
seal's cavity is pointed towards the mixer head and the
seal's split is in a downward position. This results in the
first seal's split in an upward position (D1) and the second
seal's split in a downward position(D2). Move the
seal up into the seal housing.
-
Install seal retainer plate
F on the seal housing C and bolt it in place.
-
Install collar assembly G on the blade shaft and
bolt it in place.
-
Using a torque wrench, check the torque on each
of the dust hub assembly's bolts as follows:
All 3/8 Bolts - 14 to 20 Ft.Lbs.
All 1/2 Bolts - 35 to 48 Ft.Lbs.
STEP 5
DUST HUB LUBRICATION
For the life of the dust hub seal it is
EXTREMELY IMPORTANT that grease and air be continuously
supplied to the seals. Grease is held around the dust hub
by continuous air pressure applied through fitting
H. Grease is continuously supplied to the seals through
fitting I. Follow the procedure outlined below to confirm that air
and grease are properly supplied to the seals:
- Set the air regulator of the line that goes to
fitting H on the dust hub for 5-10 p.s.i.
- Set the air regulator of the air operated lube pump
for 60-65 p.s.i.
- Set the lube pump's stroke flow adjustment to
.030 inch.
- Fill the lubrication (grease) reservoir.
- Disconnect the grease line and air line at the
seal housing (fittings H and I).
- Turn on the air pressure. Observe that air and
grease are coming out of the disconnected ends of the
grease and air lines.
- Reconnect the grease line to fitting I
and the air line to fitting H.
- Set the lube pump timer located on the mixer
control panel to a setting of 30 seconds on, 30 seconds
off. This is a starting point setting. During your daily cleanup of
the mixer you should observe slight discoloration around
the blade shafts on the head liners. This discoloration is
due to grease leaking through the seals and is normal. If
the discoloration is excessive, you may want to adjust
the lube pump timer towards a 50 seconds on, 50 seconds
off setting. This is the timer's normal setting.
- Before mixing a batch, confirm that grease is
coming out around the blade shaft. The air/grease purged dust hubs are now ready
for continuous operation.
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