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Marldon Traverse Unit |
Operating Manual
RT Range
Immediate Repair Service
If traverse units are returned to our factory for repair
or maintenance we undertake to despatch the goods back to you the following working day, and
in most cases will despatch on the same day.
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1 Operating Principle
In all Marldon linear motion drives, three special rolling ring
bearings encompass a plain round shaft. These bearings, when spring loaded to the shaft
and maintained under constant pressure, convert the rotary motion of the shaft into linear
motion at a rate that is proportional to the angular position of the rolling ring set. As a
result of this principle, a backlash free drive is assured and a high value axial thrust is
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2. Models Available - RT & TB
In 1993 the model RT was introduced. This model has a centrally mounted "T" shaped trip lever.
All critical dimensions on this model match the equivalent Uhing / Amacoil model and will
consequently substitute without any modifications to the host machine.
Before 1993 only the model TB was available. This model has the tripping lever mounted
off-centre, and the lever extends over both sides of the unit. Although its performance matches
the Uhing / Amacoil equivalent, owing to dimensional incompatibilities this model will not
simply substitute for a Uhing / Amacoil if fitted onto a Uhing / Amacoil shaft and support
arrangement.
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3. Shaft Specification
If Marldon supply the traverse shaft it will be hardened to 58 - 60 Rc.
All Marldon drives except the model RT15 will however run satisfactorily on standard ground
steel shafting of 180 - 220 brinnel hardness rating. We recommend CEAX. The model RT15 requires
a hardened shaft of 58 - 60 Rc.
Shaft diameters should be to tolerance of h6.
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4. Inserting the Shaft
a. Position the pitch control lever at 1 on the scale.
b. Move the free movement lever to the free position (horizontal). (Indicated "O")
c. Ensure that the end of the shaft is chamfered and insert the shaft into the bronze bushing
furthest from the free movement lever. Push through the unit while rotating the shaft to engage
the inner bearing set.
d. Move the free movement lever several times through the 90 degrees from "free"; to "engaged"
("O" to "I") to check that the movement is satisfactory.
e. Check the shaft rotation (see section 5). The assembly is now ready for operation.
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5. Shaft Rotation
Either direction of shaft rotation may be accommodated. However, the unit is assembled & tested
in our factory before despatch according to the customer's instructions about the intended
shaft rotation. This original factory setting is indicated on the traverse unit by an arrow
next to the bronze bush at one end of the unit. If for any reason this arrow is no longer there
or you are not sure of the history of the unit, you should check that the configuration of the
unit accords with your intended shaft rotation (as explained below).
With the black top plate and tripping mechanism underneath, and the pitch adjustment scale
facing you, do you need shaft rotation ?
top toward (TT) - that is, the shaft would roll towards you, or
top away (TA)- that is, the shaft would roll away from you?
If the trip lever is facing the wrong way, you can reconfigure the unit
by following the steps in section 6.
Those with previous experience of our competitor's (Uhing / Amacoil)
product may wish to reconcile the Marldon method of describing shaft rotation
with the Uhing / Amacoil method. It is as follows:
Uhing / Amacoil "right-hand" = Marldon "Top Toward"
Uhing / Amacoil "left-hand" = Marldon "Top Away".
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6. Reversal of Trip Lever Position - Handing
Your traverse unit will have been supplied with the trip lever configured for your intended
shaft rotation. If this configuration is no longer appropriate, you can reverse the handing
as follows.
(Important - traverses are fine tuned before despatch to ensure symmetry of travel left &
right. Fine tuning compensates for any machining tolerances which may cause unequal travel.
Occasionally this fine tuning will be negated if the traverse is used on a shaft rotating in
a direction opposite to that when originally tuned. If the speeds left & right are found to
differ, read section 11.)
a. Unscrew and remove the circular stop which limits the lever's movement (item 16)
b. Set the pitch control lever to position 9
c. Remove the legs of the springs from the trip lever (leave the other
ends in the torque arm - item 9).
d. Rotate the lever through 180 degrees to the desired position.
e. Replace the stop into the available threaded hole in the black top plate between the
2 lugs on the trip lever (now on the opposite side).
f. Replace the springs in the trip lever.
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7. Attachments
Each unit has eight tapped holes on the top surface for fitting cable guide rollers or guide
pulleys. (The inner 4 are for fitting Uhing / Amacoil equipment). Care must be taken when
fastening any items to the unit to ensure that the screws do not penetrate through the wall
thickness as they could interfere with the internal mechanism and cause malfunction
Maximum screw lengths are:
| Model |
RT15 |
RT20 |
RT30 |
RT40 |
| Max Screw Length (mm) |
8 |
10 |
10 |
12 |
Should the cable guide assemblies be carried on an independent trolley or shaft, the connection
to the traverse unit should be a non-rigid floating arrangement to avoid stresses caused by
lack of parallelism.
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8. Pitch / Speed Adjustment
Pitch is normally determined in discrete steps by positioning the Pitch Control Lever (item 21)
at the desired point on the serrated scale plate. The calibrations are intended as reference
markers only.
Fine and coarse toothed scale plates are available.
If stepless adjustment is required, a remote pitch adjustment system is available which allows
adjustment via a worm gear from a point outside the host machine.
If the pitch is to be changed only rarely, and the speeds in each direction are not required to
be the same, simple screwed adjusters (set screws) fitted in the end of the unit casing can be
offered, instead of the pitch control plate and lever mechanism.
Pitch data is given in the Pitch Data Chart (section 14)
If it is found that the unit has a different speed in each direction of travel, please read
11 below.
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9. Slip
If the linear drive is properly installed and the applied side load does not exceed the
maximum side thrust rating, the unit will provide slip free operation. Should the applied side
load exceed the unit's thrust rating, the unit will slip on its shaft without damage to any
part, provided the overload is not sustained for long periods. If the unit is required to
remain stationary while the shaft continues to rotate, the free movement lever should be moved
to the disengaged ("O") position.
Should the mechanism slip, check the following:
a. The free movement lever is not in the disengaged (horizontal) position
b. The shaft is the correct size.
If the unit has been operating for a long period it may be possible that the inner special
bearings have worn. If so, a small amount of "play" may be taken up by adjustment of the Load
Plug (item 25). See Section 10a - e "Fine Tuning" for instructions. Serious wear will
require new bearings.
If the unit has been disassembled previously, check that the disc springs are correct in number
and configured in the manner shown on the Disc Spring Arrangement Chart on the exploded diagram.
Note that reassembly should have been carried out as set out in 10i - xi, below.
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10. Side Thrust and Adjustment
Each Marldon traverse unit is factory set for optimum performance at a side thrust as shown in
the Specification Table (see Section 13), and the load plug (item 25) is marked with red
sealant to indicate original setting and to secure while not loaded. The grip that the unit has
on the shaft is set by means of this Load Plug which is found in the black top plate. After a
long period of continuous operation, normal wear can lead to a loss of side thrust. Further
adjustment of this plug can compensate for this wear. Also, if the unit has been disassembled,
it may be necessary to re-establish the side thrust. The procedure is as follows.
i. Mount the unit on the shaft, with the free movement lever in the "disengaged" ("O") position
ii. Remove the return springs (item 11) using thin nosed pliers
iii. Undo the clamping screw (item 22) in the torque arm (item 19) so that the torque arm can
be unscrewed up the threaded shaft.
iv. Turn the load plug so that it is flush with the surface of the top plate (item 2).
v. Wind the torque arm by hand on the threaded shaft until it is finger tight - do not use a
tool.
vi. Set the pitch control lever to the minimum pitch position
vii. Turn the torque arm in either direction the least distance such that it is, as accurately
as possible, in line with the axis if the traverse shaft.
viii. Tighten the torque arm clamping screw (item 22).
ix. Replace the return springs.
x. Put the free movement lever in the "engaged" position ("I")
All of the components will now be set in a balanced condition which is within a small margin of
the normal side thrust.
xi. If fine tuning is required, proceed to a) below. Otherwise, use a pointed tool to lightly
dimple the (aluminium) top plate adjacent to the load plug sufficiently to prevent it releasing.
The Fine Tuning is carried out thus:
a. With the unit mounted on its shaft, attach one end of a spring balance to it. Anchor the
other end of the balance to the side frame .
b. Set the pitch lever at setting 8 on the pitch scale.
c. Rotate the shaft until the unit slips against the pull of the spring balance. Note the side
thrust at which the slip occurs.
If the unit slips at less than its rated side thrust (per the Specification Table - see Section
13), release the free movement lever and tighten the load plug (turn clockwise) by (not more
than) 45 degrees. Put the free movement lever in "engaged" and test the side thrust again.
If the unit does not slip at its rated side thrust (per the Specification Table), release the
free movement lever and loosen the load plug (turn anti-clockwise) by (not more than) 45
degrees. Put the free movement lever in "engaged" and test the side thrust again.
d. Repeat c) using smaller adjustments each time until the appropriate side thrust for the
unit is achieved
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11. Adjustment of Symmetry
Each Marldon traverse unit is factory set to perform repeat movements left to right, and right
to left, with less than 1% error. The symmetry adjustment ring (“eccentric bush” item 40) is
marked with red sealant to indicate the original setting and to secure for transit.
If an unacceptable loss of symmetry develops, with a difference in the speed of travel from
left to right when compared with right to left, an adjustment to correct this can be made as
follows.
Note the starting position of the unit by marking the traverse shaft. Select pitch setting 2.
Rotate the shaft exactly 10 revolutions in the correct direction (per section 5). Put the unit
into reverse by manually tripping the trip lever. Again rotate the shaft in the same direction
until the unit has returned to the exact starting position. Determine the difference in the
number of shaft rotations needed for the outward movement and the return movement. If the
difference is greater than one quarter of a revolution, slacken the single socket grub screw
(item 41) in the eccentric bush (which is located on the other side of the unit from the pitch
setting scale), and rotate the ring by 15 degrees maximum as follows:
Shaft rotation is top away (TA) :
The unit travels further right than left for the 10 revolutions - rotate clockwise
The unit travels further left than right for the 10 revolutions - rotate anti-clockwise
Shaft rotation is top towards (TT)
The unit travels further left than right for the 10 revolutions - rotate clockwise
The unit travels further right than left for the 10 revolutions - rotate anti-clockwise
Repeat this procedure until the difference in the number of shaft revolutions is within
permissible limits.
Now select pitch scale setting 8 and repeat the process just described.
The grub screw (item 41) must be tightened before each test before putting the unit back
into use.
12. Maintenance
Depending on the operational environment and the frequency of use, the shaft should be cleaned
and coated with a thin layer of viscous machine oil at intervals of 2 weeks. The same oil
should also be used to lubricate the springs and bearings on the reversal mechanism.
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13. Specification Table
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| MODEL |
Shaft Diameter
(mm) |
Traverse
mm/rev
Max |
Maximum Side
Thrust Kg |
Weight
Kg |
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| RT15 |
15 |
11 |
13 |
1.0 |
| RT20 |
20 |
16 |
17 |
1.8 |
| RT30 |
30 |
24 |
28 |
3.3 |
| RT40 |
40 |
32 |
45 |
8 |
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14. Pitch Data Chart |
Approximate Pitch per Shaft Revolution *
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Model RT |
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15 |
20 |
30 |
40 |
| Setting No. |
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| 1 |
1.0 |
1.2 |
1.4 |
2.0 |
| 2 |
2.4 |
2.6 |
4.0 |
7.0 |
| 3 |
3.8 |
4.4 |
7.0 |
10.0 |
| 4 |
5.0 |
6.4 |
10.4 |
15.0 |
| 5 |
6.6 |
8.6 |
13.8 |
18.0 |
| 6 |
8.0 |
10.6 |
17.6 |
23.0 |
| 7 |
9.0 |
12.7 |
20.8 |
26.0 |
| 8 |
10.0 |
14.6 |
24.2 |
29.0 |
| 9 |
11.0 |
16.3 |
26.0 |
31.0 |
| 10 |
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33.0 |
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| * Note : Please note that the increase in pitch is NOT a linear function. |
Contact Points
Tel: +44 (0)870 907 0015
Fax: +44 (0)870 907 0014
E-mail : sales@marldon.com
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