11.1 Removing the cover (04) (see fig. 10)
❑
Unscrew the screws (43). Use the two threaded holes on the cover (if present) to facilitate removal of the cover.
❑
When removing the cover, take care not to damage the gasket (31). If this is damaged it should be replaced. Do not use damaged gas-
kets or gaskets with a thickness different from that of the original gasket.
❑
Slide the cover/idler assembly carefully out of the pump casing. Attention: when the cover is removed, the idler may fall off the idler pin if
it is not held. This is a potential cause of accidents.
❑
If the pump mounts a by-pass relief valve (figure 11) on the cover it is not neces-
sary to remove it. If, however, the by-pass also requires maintenance, unscrew the
screws (46) and remove it, taking care not to damage the gasket(s) (32). If the
gaskets are damaged, replace them.
❑
If the pump mounts a heating jacket on the cover (R2 (07), this will sepa-
rate from the cover as soon as the screws are removed (43), see figure 11.
❑
Take care not to damage the gaskets; if this should happen, replace it.
❑
If the cover/idler assembly does not require maintenance, go to paragraph 4.6.
11.2 Removing the idler (03) (see fig. 10)
❑
Slip the idler off the idler pin (06). The idler bush is fitted to the centre of the idler.
(Some versions do not have an idler bush and mount a large diameter pin.)
❑
The idler bush can be supplied in various different materials. The choice of mate-
rial depends on various factors such as the liquid to be pumped and the duty.
❑
Remove the used idler bush using a bench press. The bush is usually press fitted.
❑
Clean the bush thoroughly and check the surfaces for wear. Replace the bush if it
has external or localized cracks, signs of abrasion, severe wear, deformation,
external or localized blackening, rust, etc. The tolerances and clearances of the
bush depend on the pump version and the specific application for which it is
intended. It this therefore not advisable to replace bushes with other of similar
dimensions or of different materials from the original. This could cause damage to
the pump.
Note: the bushes play an essential role for the satisfactory operation of the pump.
They have been designed and tested to ensure perfect contact between the idler
and idler pin and between the shaft and the rear cover.
Do not invent alternative solutions or try to repair the bushes by changing
the tolerances or chemical and mechanical characteristics.
❑
After removing the bush, clean the idler thoroughly and inspect the surfaces.
❑
If there are clear signs of severe wear or the hole is ovalized, replace the idler.
❑
Mount the new bush using a bench press with a steady movement. For the V180,
V200, heat the idler to 80 deg C and mount the bush. Use a lathe to bring the hole
up to tolerance as instructed by Varisco.
11.3 Removing the idler pin (06) (see fig. 10)
❑
The idler pin is fixed to the cover. The pin should be removed only if it needs to be
replaced or when replacing the cover. It is not necessary to remove it to check the
state of wear. The working surface where the idler bush runs sticks out complete-
ly from the cover.
fig 10
fig. 12
fig. 11
10
