The shaft seals are
classified according to:
- their outer configuration
- geometry of their sealing lip.
ST:
Plain rubber-coated profile.
This type is in almost universal use.
It guarantees a perfect seal even if
installed in seats with a high surface
roughness and in the presence of
low viscosity fluids. It provides an
excellent compensating action
against the thermal expansion of
metals.
RT: Corrugated
rubber-coated profile. It varies with respect to the standard type by the
presence of a corrugation on the outer surface. It
offers the advantage of being more
easily installed.
RM: Bare metal
case, rectified or
calibrated.
It is normally used where the following is required:
- high pulling loads
- very small differences between the
housing diameter and the shaft diameter
-need to economize on the use of
high-quality elastomers.
It demands particular care and precision making the housing seats.
CRM: Partially
rubber-coated metal
case with a corrugated face.
This type combines the advantages
of the RT and RM models: it guarantees a fluid seal and compensates
for the thermal expansion of the metals,
at high pulling loads.
4.2.2 - Geometry of the sealing lip
ST: Lip loaded
by a Garter spring: suitable
for most applications.
RP: Lip loaded
by a Garter spring and
equipped with an additional dust
cover. It is suitable
for all those applications where it is necessary, in addition to the
main sealing function, to prevent
the infiltration of dust, mud or
other impurities from the outside. Before
starting to install this ring it is
advisable to grease the space between
the sealing lip and the dust cover
lip. The grease fulfills the double duty of lubricating the dust cover
and protecting the shaft from any
corrosion induced by humidity. It
can be supplied in a version including several dust cover lips.
RD: Two
opposing lips with their relative
Garter springs. It is
suitable for ensuring the seal between
two different liquids. As for the
RP model, it is also advisable to grease
the space between the sealing lips in this case.
RDS: It has
the same characteristics as
the previous model, but is recommended
for operating on rotary
shafts with high rotary speeds,
under poor lubricating conditions. It guarantees a perfect seal against
internal vacuum conditions and
external impurities. It finds particular application on two-stroke
engines and racing engines.
It can be supplied in
a RPS version
(equipped with a special
dust cover lip).
LSM: Lip
without spring. It is
recommended in case of space limitations
and where performance is
not demanding (for instance, a grease
seal and a low rotary speed).
Type "R" with
a hydrodynamic effect.
Its rear contact face is
fitted with relief
grooves of a variable geometry (generally obtained by pressing) and
helical arrangement, whose purpose
is to aspirate small quantities of oil, if these should pass through
as a result of high rotary speeds.
This type of shaft seal is in fact
suitable for solving sealing problems arising under conditions of
high surface speed and high
shaft eccentricity
and/or knocking.
The fundamental versions of the "R"
type are:
Monodirectional grooved:
RDX: Garter
spring-loaded lip with helical
grooving and right-hand orientation.
Suitable for operating on
shafts having a
clockwise rotation.
RSX: Garter
spring-loaded lip with helical
grooving and left-hand orientation.
Suitable for operating on
shafts having a
counterclockwise rotation. To
ensure their proper application, these
shaft seals carry an arrow etched
on the bottom (rear surface) and
pointing in the shaft's compulsory sense of rotation.
Bidirectional grooved:
RBD: Garter
spring-loaded lip with a twin
helical grooving. It
is suitable for operating on shafts with
a clockwise and counterclockwise rotation. Lab tests
have shown that the hydrodynamic index of the monodirectional shaft
seal is superior to that of a similar
bidirectional shaft seal. On
shafts rotating in only one direction it is therefore always preferable
to resort to the monodirectional version.
The bi-directional shaft seal should
be used on shafts rotating in both
directions whenever the plain lip
shaft seal cannot offer adequate guarantees
of proper performance.
RPAP: Garter
spring-loaded lip, shortened
with respect to the RP type
and equipped with an additional protruding dust cover lip. It
is suitable for all applications having
an operating pressure in the range
of 0.5 to 6 bar.
This type of shaft
seal does not require the presence of a supporting ring (see par.
5.5).
It is particularly recommended for
applications on industrial pumps.
AP: Garter
spring-loaded lip of a special
profile. It can be
supplied with or without an additional
dust cover lip. It is suitable for applications where the operating
pressure is in the range from 6
to 20 bar , and can be
utilized
without the
aid of supporting rings.
FL:
Stainless-steel Garter spring-loaded lip fitted with one or more additional
dust cover lips and an outer
diaphragm with a variable geometry
designed to provide a static seal. The
particular configuration of the seal
profiles affords the possibility of
filling out the spaces between the lips
with a quantity of grease exceeding that of a traditional ring. It
is particularly used in the household appliance sector, on washing-machine
basket shafts, serving
as a seal between lyes and bearing
lubricating grease.
DRL FL: Same
characteristics as for the
FL type, but with a greater grease retaining capacity. This
is achieved by assembling 2
rings. It
is preferable to the type FL, due to its
advantage of having a longer life.
MV: A shaft
seal especially designed to guarantee a sealing action on
rotating shafts having a simultaneous axial motion, and in the presence
of heavy external contamination (dust, water, and mud). It
finds wide application by manufacturers of axles for tractors and for
earth moving equipment. It
can be supplied with
a polyurethane insert of
variable geometry and with various
types of materials: MVC
(cellular
polyurethane insert) MF
(felt insert).
It is alternatively possible
to apply a "box-type"
ring consisting in a sealing system with a built-in counterface and
"labyrinth-type" sealing lips.
It finds application where
the housing rotates and not the shaft (for instance,
in wheel hubs).
RC: Same
characteristics as for the RM
type, but with an additional metal
innercase, built-in and fastened. Recommended
over the RM type whenever
a thorough protection of the
sealing lip is required when moving
and installing large size mechanical
parts.
4.2.3 -
Shaft seals for shafts with axial
reciprocating motion
The ROLF products range also includes shaft seals designed for use on
mechanical units equipped
with shafts having an
axial motion. These
articles differ from the previous in their basic design, and are therefore
dealt with separately from those
already described. Depending on
their application, they are classified as follows:
- Shaft seals for steering control units:
BR, WBR
- Shaft seals for bike and motorcycle forks:
SFRD, SFRP, SFRH, SFMT
- Shaft seals for automotive and motorcycle
shock absorbers: AMRP.
Shaft seals for steering control units
BR: Garter
spring-loaded lip of a special
configuration, fitted with a thermoplastic
supporting insert. It
is suitable for all those applications where the working pressure is in the range from 20 to 140 bar and
for
linear velocities of 0.03 m/sec. It
is typically used as a sealing gasket
on power-assisted rack-and pinion
steering systems.
WBR: Same
characteristics as in the BR
model, but without a thermoplastic supporting insert. It
is suitable for applications with a pressure
range of 20 to 100 bar
and a linear velocity
of 0.03 m/sec.
Shaft seals for forks
SFRD:
Special
shaft seal for hydraulic forks. Suitable
for sealing against pulsating pressures, in the presence of shaft
eccentricity and heavy external contamination (by water, mud, dust
etc.). It can be
supplied in all external configurations
and with a sealing lip in
an RP version: SFRP.
SFRH: Special
shaft seals for forks, acting
as dust scrapers on stem surfaces and for protecting internal sealing
gaskets (type SF) from external
contaminants (mud, water,ice, etc.). It
can be supplied in the following versions:
with a spring,
without spring,
or made of a
polyurethane plastic material.
SFMT: Special
shaft seal for mechanical forks: particularly
suitable for acting as a seal
against the fluid inside the system
(generally grease) and, at the
same time, to insulate against the
presence of heavily contaminating external agents (water, mud, dust).
It can also be supplied in a version
without the spring.
Shaft seals for shock
absorbers
AMRP:
Shaft
seals for shock absorbers. Suitable
for applications on shafts with
reciprocating motion and high, pulsating
pressures. Positive
insulation against external impurities.
It finds particular
application in the motor
vehicle and motorcycle industry. It
can also be supplied in the versions without additional dust cover
lip: AM.
ST:
Plain rubber-coated profile.
This type is in almost universal use.
It guarantees a perfect seal even if
installed in seats with a high surface
roughness and in the presence of
low viscosity fluids. It provides an
excellent compensating action
against the thermal expansion of
metals.
RT: Corrugated
rubber-coated profile. It varies with respect to the standard type by the
presence of a corrugation on the outer surface. It
offers the advantage of being more
easily installed.
RM: Bare metal
case, rectified or
calibrated.
CRM: Partially
rubber-coated metal
case with a corrugated face.
This type combines the advantages
of the RT and RM models: it guarantees a fluid seal and compensates
for the thermal expansion of the metals,
at high pulling loads.
RP: Lip loaded
by a Garter spring and
equipped with an additional dust
cover. It is suitable
for all those applications where it is necessary, in addition to the
main sealing function, to prevent
the infiltration of dust, mud or
other impurities from the outside. Before
starting to install this ring it is
advisable to grease the space between
the sealing lip and the dust cover
lip. The grease fulfills the double duty of lubricating the dust cover
and protecting the shaft from any
corrosion induced by humidity. It
can be supplied in a version including several dust cover lips.
RD: Two
opposing lips with their relative
Garter springs. It is
suitable for ensuring the seal between
two different liquids. As for the
RP model, it is also advisable to grease
the space between the sealing lips in this case.
RDS: It has
the same characteristics as
the previous model, but is recommended
for operating on rotary
shafts with high rotary speeds,
under poor lubricating conditions. It guarantees a perfect seal against
internal vacuum conditions and
external impurities. It finds particular application on two-stroke
engines and racing engines.
It can be supplied in
a RPS version
(equipped with a special
dust cover lip).
LSM: Lip
without spring. It is
recommended in case of space limitations
and where performance is
not demanding (for instance, a grease
seal and a low rotary speed).
RDX: Garter
spring-loaded lip with helical
grooving and right-hand orientation.
Suitable for operating on
shafts having a
clockwise rotation.
RSX: Garter
spring-loaded lip with helical
grooving and left-hand orientation.
Suitable for operating on
shafts having a
counterclockwise rotation. To
ensure their proper application, these
shaft seals carry an arrow etched
on the bottom (rear surface) and
pointing in the shaft's compulsory sense of rotation.
Bidirectional grooved:
RPAP: Garter
spring-loaded lip, shortened
with respect to the RP type
and equipped with an additional protruding dust cover lip. It
is suitable for all applications having
an operating pressure in the range
of 0.5 to 6 bar.
This type of shaft
seal does not require the presence of a supporting ring (see par.
5.5).
It is particularly recommended for
applications on industrial pumps.
AP: Garter
spring-loaded lip of a special
profile. It can be
supplied with or without an additional
dust cover lip. It is suitable for applications where the operating
pressure is in the range from 6
to 20 bar , and can be
utilized
without the
aid of supporting rings.
FL:
Stainless-steel Garter spring-loaded lip fitted with one or more additional
dust cover lips and an outer
diaphragm with a variable geometry
designed to provide a static seal. The
particular configuration of the seal
profiles affords the possibility of
filling out the spaces between the lips
with a quantity of grease exceeding that of a traditional ring. It
is particularly used in the household appliance sector, on washing-machine
basket shafts, serving
as a seal between lyes and bearing
lubricating grease.
DRL FL: Same
characteristics as for the
FL type, but with a greater grease retaining capacity. This
is achieved by assembling 2
rings. It
is preferable to the type FL, due to its
advantage of having a longer life.
MV: A shaft
seal especially designed to guarantee a sealing action on
rotating shafts having a simultaneous axial motion, and in the presence
of heavy external contamination (dust, water, and mud). It
finds wide application by manufacturers of axles for tractors and for
earth moving equipment. It
can be supplied with
a polyurethane insert of
variable geometry and with various
types of materials: MVC
(cellular
polyurethane insert) MF
(felt insert).
It is alternatively possible
to apply a "box-type"
ring consisting in a sealing system with a built-in counterface and
"labyrinth-type" sealing lips.
It finds application where
the housing rotates and not the shaft (for instance,
in wheel hubs).
RC: Same
characteristics as for the RM
type, but with an additional metal
innercase, built-in and fastened. Recommended
over the RM type whenever
a thorough protection of the
sealing lip is required when moving
and installing large size mechanical
parts.
BR: Garter
spring-loaded lip of a special
configuration, fitted with a thermoplastic
supporting insert. It
is suitable for all those applications where the working pressure is in the range from 20 to 140 bar and
for
linear velocities of 0.03 m/sec. It
is typically used as a sealing gasket
on power-assisted rack-and pinion
steering systems.
WBR: Same
characteristics as in the BR
model, but without a thermoplastic supporting insert. It
is suitable for applications with a pressure
range of 20 to 100 bar
and a linear velocity
of 0.03 m/sec.
SFRD:
Special
shaft seal for hydraulic forks. Suitable
for sealing against pulsating pressures, in the presence of shaft
eccentricity and heavy external contamination (by water, mud, dust
etc.). It can be
supplied in all external configurations
and with a sealing lip in
an RP version: SFRP.
SFRH: Special
shaft seals for forks, acting
as dust scrapers on stem surfaces and for protecting internal sealing
gaskets (type SF) from external
contaminants (mud, water,ice, etc.). It
can be supplied in the following versions:
with a spring,
without spring,
or made of a
polyurethane plastic material.
SFMT: Special
shaft seal for mechanical forks: particularly
suitable for acting as a seal
against the fluid inside the system
(generally grease) and, at the
same time, to insulate against the
presence of heavily contaminating external agents (water, mud, dust).
It can also be supplied in a version
without the spring.
AMRP:
Shaft
seals for shock absorbers. Suitable
for applications on shafts with
reciprocating motion and high, pulsating
pressures. Positive
insulation against external impurities.
It finds particular
application in the motor
vehicle and motorcycle industry. It
can also be supplied in the versions without additional dust cover
lip: AM.