Installation Procedure | SCHNEEBERGER Precision Gear Racks

6. Installation

6.1 Fitting the first and additional gear rack(s)

Picture 1: Chamfer between the installation and contact surfaces of the gear rack (R<1.8)

The gear rack has a chamfer between the installation and the contact surfaces (Picture 1) in order to ensure it abuts the machine bed as cleanly as possible.

The gear rack will be aligned in the best possible way if the stop bar is first of all aligned with the guide blocks. Attach the first gear rack to the machine bed, align it centrally, and then clamp it to the installation surface with the screw clamps (Picture 2).

Fitting the first gear rack with screw clamps

Picture 2: Clamping the first gear rack with screw clamps

Picture 3: Placing the fixing screws

Attach the fixing screws but do not tighten them fully
Position the gear rack's contact surface in accordance with the guideway of the machine
Then tighten the fixing screws with an appropriate torque from the middle outwards (see Chapter 12)

Picture 3 (cont.): Fixing screws attached

Repeat the previous steps for the remaining cylinder screws. The screw clamps can then be undone.

Picture 4: Fixing screws tightened, screw clamps removed

The flatness and joints of the fitted gear rack must be checked before the next gear rack is attached. Position the next gear rack over the corresponding fixing holes.

Picture 5: Fitting the next gear rack using the assembly jig (BZM)

Attach the assembly jig (BZM) and clamp it lightly
Clamp the gear rack to the machine bed in the area of the fixing holes
Insert the first fixing screw in the direction of installation
Tighten the fixing screw with an appropriate torque in the direction of installation
Repeat the previous steps for the remaining fixing screws
Undo all screw clamps and the assembly jig

Recommendation: We recommend using a screw securing adhesive (e.g. Loctite 243) to secure the fixing screws.

Gear racks can be fitted in any order. However, if the gear rack is shorter than 1 metre, dowel pins are also necessary. Ensure that only gear racks with identical order codes are used for the same application.

The systems must be aligned in an axial direction over the tooth racks in such a way that the pinion does not jam when rolling over the joint. To do this, the spacing of the teeth must be set at the joint so that it corresponds with the spacing of the remaining racks and thus moves within the permissible individual pitch error of the adjacent rack.

To do this, the assembly jig (BZM) should be used for installation. This is a short rack segment with counter gearing. After the guide rails have been orthogonally aligned, they are pulled into the gearing using a clamp, and in this way the systems are axially aligned with one another. To do this, at least one of the aligned segments must be moved slightly in an axial direction.

Notes on tensioning gears

Note: If the torque is transferred via a tensioning gear or a tensioning system in which two gear wheels are meshed on the same gear rack, the whole torque must not exceed the push force of the screws.

6.2 Checking the running accuracy

Fix the dial gauge bracket onto the machine slide
Put the measuring roller in the tooth rack on the left (A), the joint (B) and the tooth rack on the right (C), and measure the difference in height in each case with the dial gauge. The permissible height difference depends on the quality grade of the gear racks
The joint (B) should be between the upper and lower limit of the left (A) and right (C) tooth racks

Checking running accuracy with a dial gauge

Running accuracy measurement: A = left tooth rack, B = joint, C = right tooth rack

In the event of large deviations, use a copper tapered punch to hit the first screw hole of the previous gear rack (away from or in the direction of installation) in order to reach the height tolerance indicated on the dial gauge
After the joint has been checked successfully, clamp the screw clamps on again, tighten them lightly once more, and tighten the cylinder screws with full torque (see Chapter 12)
Repeat the previous steps for the other gear racks
Remove the screw clamps

6.3 Pinning

Drill the pin holes to match the gear rack holes in the machine bed.

Ream all the holes to the correct tolerance dimension for the dowel pins (see Section 5.2).

Remove any swarf with a vacuum cleaner.

Finally, fix the gear racks with cylinder pins.

Recommendation: We recommend dowel pins with an internal thread for easier removal (see Section 5.2).

6.4 Final check

If necessary, remove the grease from the tooth flanks of the gear rack
Paint the tooth flanks with touch-up paint
Move the machine table several times so that the pinion runs over the painted tooth flanks
While doing this, check that the tooth rack moves easily
The energy expenditure and the running noise must be the same over the whole travel distance
There must be no impact at the joints
Check the area where the paint was removed from the tooth flanks to assess the fit of the gear
Assess the alignment of the gear using the contact pattern shown below
If necessary, adjust the alignment of the gear
Check the gear racks at the joint for pitch accuracy