Zenith Pumps manual Reassembly

Reassembly	These instructions should be thoroughly
	read and understood before starting
	reassembly.
	General instructions that should be
	observed to ensure correct reassembly
	of the pump are as follows:
	• Using a solvent such as
	trichloroethane or chloroethene Nu,
	clean all parts that are to be used in the
	reassembled pump.
	WARNING: Use extreme care when using
	any solvent. Prolonged contact with the
	liquid or inhalation of the vapor can cause
	serious health problems.
	• During and between each of the
	assembly steps, manually turn the
	metering gears to ensure that they are
	free turning. If binding occurs at any time
	during assembly, determine the cause
	and correct it before proceeding further.
	A tiny nick, burr or foreign particle can
	extensively damage a valuable part if
	allowed to remain. Never use excessive
	force in assembling or turning a pump. If
	properly aligned, the pieces will fit easily
	into the plate, and the drive shaft will turn
	freely. All seals, O-rings and fasteners
	must be replaced with new parts prior
	to assembly.
	• Use a soft-jawed vise to hold the
	pump during reassembly.
	• Before installing screws, lubricate
	their threads with DAG Dispersion 154,
	Felpro C-100, or similar heat-resistant
	lubricant, and torque to prescribed values
	as shown on the table on page 10.
	1) On 3.0 cc/rev and smaller pumps,
	place a gear key on each shaft and slide
	each gear onto its shaft, engaging the key.
	2) Slide the gear shafts into the center
	plate, taking care not to damage the gear
	teeth. On 3.0 cc/rev and smaller pumps,
	note that each shaft has a larger diameter
	end. These larger ends must be on oppo-
	site sides of the pump for the bearing
	grooves to align properly.
	3) Gently slide the gear shafts so that
	the rear ends of the shafts protrude from
	the rear of the center plate. On the 3.0
	cc/rev and smaller pumps, take care not
	to slide the shafts out of the gears and
	allow the keys to drop out of the shafts.
	4) Slide a bearing onto the drive shaft,
	taking special care to select a bearing
	with the proper groove configuration (and
	with the proper ID on the 3.0 cc/rev and
	smaller pumps). Slide the matching bear-
	ing onto the driven shaft, taking care to
	select a bearing with the proper groove

configuration. Set the flats on the circum- ference of the bearings against each other, and gently slide the bearings and shafts into the center plate. Slide them far enough through the center plate to allow the drive shaft to protrude out on the front side and allow the front bearings to be installed. See D-bearing orientation schematic on page 8.

5)Install the front bearings in the same manner as the rear bearings, and slide the bearings and shafts back into the center plate so that the gears are roughly in the center of the center plate.

6)For the 20 cc/rev and smaller pumps, the bearings should be allowed to protrude very slightly above the face of the center plate before the cover plates are installed. This will allow the bearings to fit flush against the cover plates as there are no bearing screws on these smaller pumps. For 20 cc/rev and smaller pumps, insert the bearing locating keys on each side.

7)At this point make certain again that there is no foreign matter on the faces of the cover plates or on the faces of the center plate. An accidental smudge of thread lubricant can cause the small pumps to bind.

8)Place the front cover plate on the pump (and center on pump), checking one more time that the configuration of the bearing grooves is correctly oriented for the inlet and discharge ports of the pump. Insert the lubricated cover plate screws into the pump and tighten them finger tight only. Repeat for the rear cover plate.

9)On the 40 cc/rev and larger pumps, insert the bearing retainer screws and tighten them finger tight at this time.

10 Torque down the cover plate screws in a crisscross pattern, taking them first to 1/4 the recommended torque value, then to 1/2, to 3/4 and finally to their full recommended torque value.

11) Torque down the bearing retainer screws in the same manner as the cover plate screws. (Install C-Rings if applicable.)

12)Fit the Rheoseal seal housing to the shaft. Loosely install but do not torque down the seal housing screws, as this will allow the lip seal to properly center the housing.

13)Install the lip seals, using the special Zenith installation tools as follows to prevent damaging the seal. Install the lip seals with the open face toward the body of the pump. Slide the installation

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