MK Plastics DHK-NW IO&M - Manual (Page 6)

M.K. Plastics Corp. Montréal, Québec www.mkplastics.com Page. 6
Removal of Wheel, Shaft & Bearings -
1. Mark the position on the shaft of both bearing races,
setscrews (if applicable) and the wheel and sheave. If
you are replacing the shaft as well, these marks will give
you reference.
2. Mark the location and orientation of the inlet cone and
sleeve to the casing and remove, this will give you
access to the wheel. Remove the drive sheave from the
shaft
3. Start wheel removal by unscrewing the front protective
cap and then the nut, washers and threaded stud
assembly that holds the cap to the fan shaft. The exposed
bushing has hex screws that secure the bushing to the
shaft; they are situated on the front face of the bushing.
Unscrew the hex screws, remove and screw back into
the other exposed holes of the bushing. By doing this
you are pushing the bushing out. Remove and then use
a 2-jaw puller to extract the bushing if needed. When the
bushing is out, the wheel and hub assembly can now be
removed from the fan shaft. Note: DHK 1225 to 1500
sizes do not have bushings, the wheel is held in place to
the shaft with the threaded rod assembly only.
4. Unbolt the bearing housing hold-down bolts and remove
the shaft and bearings as one unit. Keep any existing
shims in place.
5. Unbolt the top housing section and remove the bearing
assemblies from the shaft. A suitable puller may be
required, or tap on the bearing with a wood block and
hammer to remove. If the bearings are attached with
set screws, unscrew and slide the assembly off as one
piece.
6. If the existing shaft is being used, check the shaft for
nicks, burrs and damage. Remove any anti-corrosion
coating with a suitable degreaser and wipe clean.
Bearing Replacement [Split Housing Bearings With
Adapter Sleeves] -
1. Split pillow block bearings come in kits with bearings,
adapter sleeve, locknut, lock washer and fixing rings for
the rear fixed bearing. NOTE: replacement bearings will
be shipped temporarily assembled on a shaft.
2. Remove the top half of the bearing housing to expose
the bearing seat.
3. Place the lower half of the bearing housings in position
on the stand and tighten the fixing bolts.
4. Spherical split pillow block bearings use synthetic rubber
seals that come in split (half) sections. One half should
be inserted into the lower bearing housing on both sides
and some grease applied prior to the bearing assembly.
5. Place the bearings in the lower half of the housings with
the larger sides of the bores facing towards the shaft
ends.
6. Slide the adapter sleeves through the bearings, ensuring
that the threads are facing each other.
7. Install the lock washers on the adapter sleeves with
inner prong of washer in a slot on the adapter sleeve.
Install the locknut on both bearings with the chamfered
face facing the bearing, but do not tighten.
8. Slide shaft through both bearing assemblies. If the
bearing locks to the shaft, tap gently on the adapter
sleeve to loosen.
9. To hold the shaft in place during wheel mounting, clamp
the sheave end of the shaft to the edge of the stand.
10. Install the wheel and bushing on the shaft. Install the inlet
cone in its original location. Position the wheel correctly
by moving the shaft axially in the bearing assemblies.
11. Install fixing rings on the rear bearing (closest to sheave).
Move shaft axially so that the fixing ring may be inserted
between housing shoulder and bearing outer ring.
12. Tighten locknuts to fasten the bearings to the shaft,
using a spanner. While tightening, regularly measure
the internal bearing clearance between the most vertical
unloaded roller and outer ring with a feeler blade. When
required clearance is obtained (check table), tighten
locknut until the closest washer tab meets a slot on the
locknut.
13. Fill the lower housings with grease until the rollers are
covered.
14. Carefully align the top part of the housing with the dowel
pins and tighten bolts, ensuring that the upper seals
are in place. Make sure that the split housing is paired
only with its original top half, as these parts are not
interchangeable from one housing to another.
Bearing Replacement [Closed Housing Bearings With
Setscrews] -
1. Making sure that the set screws are not protruding from
the inner bearing rings, slide the bearings directly onto
the shaft. If using an old shaft, make sure the bearings
are not mounted on a worn section. Tapping the inner
ring face with a soft driver might be required.
2. The outer ring of the bearing is spherical and swivels
in the housing to compensate for misalignment. Secure
the housing to the stand with the fixing bolts, but do not
fully tighten.
3. Install the wheel on the shaft. Install the inlet cone in its
original location. Position the wheel correctly by moving
the shaft axially in the bearing assemblies.
4. Tighten the setscrews on the bearings to secure the
shaft. Refer to torque chart on Page 7.
5. Rotate the shaft by hand to allow the bearing outer rings
to find their center of free movement.
Test Run -
1. Re-install the sheave and adjust the belt tension.
2. Test run and retighten all setscrews and fixing bolts; trim
balance as necessary.
Changing Shaft Speed
All belt driven fans with motors up to and including 5 HP
are equipped with variable pitch pulleys. To change the fan
speed, perform the following:
1. Loosen setscrew on driver (motor) pulley and remove
key, if equipped.
2. If the pulley has multiple grooves, all must be adjusted
to the same width.
3. After adjustment, inspect for proper belt tension.
4. To reduce speed, open the pulley in order that the belt
rides deeper in the groove (smaller pitch diameter).
5. To increase speed, close the pulley so that the belt rides
higher in the groove (larger pitch diameters). Make sure
the maximum fan RPM and motor HP is not reached.