36
Servicing/Inspection
The zero gravity balancer must be serviced continuously. All
external moving parts as well as the friction points on the
suspension and spring hook must be greased. For cable
care, we recommend non-corrosive grease because it signi-
ficantly increases the cable’s useful life.
The suspension, the safety chain, the spring hook and the
cable (complying with DIN 15020, Part 2) must be monito-
red continuously and needs to be checked by a competent
person at least once a year. If damage (such as broken
strands, “cage-type” bulging, flattened places or abrasion)
is found on the cable, or if any of the above-mentioned
parts show significant signs of wear and tear, the balancer
must be withdrawn from service and replaced immediately.
Should the cable, spring or other parts of your zero gravity
balancer need to be replaced, our customer service depart-
ment has pre-assembled replacement sets available.
Maintenance
The following sections refer exclusively to our pre-assem-
bled replacement sets: cable, spring & cable drum, hou-
sing, and suspension. Be sure to use only genuine spare
parts for replacement.
When replacing any of the above-mentioned components,
always follow the Operating Instructions supplied with the
product.
Replacing the cable
This type of zero gravity balancer allows you to replace the
cable without releasing the spring tension or taking the
system apart.
Pull out the cable up to the cable extension limit stop, then
press the blocking device to unlock the cable extension
stop mechanism and pull out the cable as far as possible
(the cable coupling/mount is now visible in the lower region
of the housing slot).
Using a screwdriver, lock the cable drum by first pressing
the locking bolt of the drum lock (10) inwards as far as it will
go and then turning it clockwise by approx. 90 degrees.
Make sure that the bolt is securely arrested and the cable
drum securely locked as a result! Remove the working load.
Disengage the cable by pushing it back into the housing
(use a screwdriver for support if required), then remove it.
Take a new cable and bend it slightly towards the cable
drum, then push it through the housing slot and anchor it in
the drum. Be sure to install the cable correctly: it must
engage noticeably with the guiding groove.
An incorrectly anchored cable may slip out of its
coupling under load and cause injuries or other dam-
age as a result of the load crashing down!
Hook the load and unlock the cable drum by pressing down
the locking bolt (10) again, then turning the unloaded bolt
anticlockwise until it disengages and snaps back into its ori-
ginal position.
Replacing the spring assembly with
the spring fracture safeguard
(A) Removal:
Retract the cable fully, then remove the load. In the event of
spring fracture, lock the cable drum as described under
Replacing the cable.
Take the zero gravity balancer off its suspension.
Release the spring tension, proceeding as follows:
Apply a size-19 socket spanner to the endless screw (9),
then turn the spanner in the direction of the “-” symbol until
the cable no longer retracts. The spring fracture safeguard
blocks the cable drum.
To prevent spring destruction, do not slacken it too
much!
Unscrew the housing cover and the cable drum cover, then
remove the spring assembly from the drum. For models with
two spring assemblies (type 7251-08 or higher): Remove the
upper spring now. Should the lower spring assembly still
have some residual tension, unload the spring completely by
rotating the endless screw (9) in the “-” direction. Thereafter,
take the lower spring assembly out of the drum as well.
When replacing the spring assembly following spring
fracture, the housing, the cable and the cable drum
must be checked for damage and replaced as well
where indicated, as high dynamic forces are released
when spring fracture occurs and the spring fracture
safeguard mechanism is activated as a result of this.
Replace the damaged spring by a new spring assembly. If a
spring of a different strength is used, the type and load ran-
ge details must be changed accordingly on the rating plate.
(B) Reassembly/Reinstallation:
The spring assembly label must be visible when inserting
the spring assembly.
After a spring fracture: Unlock the drum lock (see descrip-
tion under Replacing the cable) and wind up the cable by
rotating the cable drum until the cable stop buffer comes up
against the mouth of the housing.
Insert the spring assembly into the cable drum, pressing the
external lever of the cable fracture safeguard against the
spring assembly.
To ensure proper functioning, the external spring suspen-
sion must engage with the drum slot and the internal spring
suspension must engage with the shaft groove; if necessa-
ry, turn the shaft a little with the endless screw (9) to enable
the spring suspension to glide into the shaft groove.
First, screw the cable drum cover in place, then the housing
cover, using new tooth lock washers.
Apply the cover disk of the worm gear and screw it in place.
Tensioning the spring:
To set the maximum initial tension (preload), rotate the shaft
“X” times by turning the endless screw (worm) in the “+”
direction:
7251-01
X = 4
3
/
4
7251-09
X = 5
1
/
4
7251-02
X = 5
3
/
4
7251-10
X = 3
1
/
2
7251-03
X = 4
3
/
4
7251-11
X = 3
1
/
4
7251-04
X = 4
1
/
2
7251-05
X = 3
3
/
4
7251-23
X = 4
3
/
4
7251-06
X = 3
1
/
2
7251-24
X = 5
3
/
4
7251-07
X = 3
1
/
4
7251-25
X = 4
3
/
4
7251-08
X = 4
1
/
4
7251-26
X = 4
1
/
2
7261-01
X = 5
7261-04
X = 5
1
/
4
7261-02
X = 4
3
/
4
7261-05
X = 3
1
/
2
7261-03
X = 5
1
/
4
7261-06
X = 4
1
/
2
Install the zero gravity balancer as described under Instal-
lation and adjust the load as described under Adjusting
the working load.
Never open the spring assembly! Defective springs
must be properly disposed of.
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