Best practices for turnout, crossing diamond grinding

Railway Track and Structures, July, 2000 by David Davis, Don Guillen, Satya Singh, V. Terrill, D. Mesnick

Grinding equipment has improved. The most-preferable production grinding machines can produce the desired profiles, with little removal of excess metal. Twenty stone grinders are typically used.

Due to a lack of accuracy and consistency, production grinders are not used in the critical switch point and frog point areas. Dropping a grinding wheel inaccurately in these areas could over-grind, chip, or break the point.

Premium materials are recommended for use throughout heavy-haul special trackwork, including closure rails, guard rails and frogs.

Use of premium guardrails and gauge plates have kept wheels and frogs in better alignment.

Spring frogs are now standard on two railroads for heavy-haul mainline turnouts. Spring frogs eliminate the open flangeway for mainline traffic and reduce the amount of grinding needed on frogs.

Elimination of joints through the use of fully-welded turnouts has also decreased the amount of grinding required.

Improved performance from special trackwork and routine running surface maintenance in rail has led some railroads to adopt a preventive-grinding philosophy.

In this approach, the running surface profile is maintained at shorter tonnage intervals. The running surface is re-shaped to the desired profile with little additional metal removal.

This approach requires skilled interpretation of profile measurements to minimize grinding metal "loss." Training is essential for field personnel.

Optimal point profile

There is no universal agreement on an optimal running surface profile in areas where the wheel transitions from one running surface to another, such as at the switch point or frog point.

Most grinders try to restore the original profiles, recognizing that these profiles are likely to rapidly deteriorate again.

Future work

This AAR research program follows the survey with investigation of the highlighted research needs and appropriate field tests of grinding practices. Among the research and development needs noted are:

* Stronger flow-resistant materials

* Elimination of open flangeway gaps (via spring frogs, movable-point frogs and flange-bearing frogs)

* Improved production grinders that are more accurate and flexible (i.e., require less passes to accomplish task)

* Production grinders that can work through road crossings, switches and frogs

* Improved easy-on/off grinders are needed to reduce grinding intervals

* Improved spot grinders that are more accurate and flexible

* Better accommodation of hollow-tread wheels

* Larger switch risers, longer frog point slopes

* Design a better plate to help maintain a solid-stock rail/switch point/switch plate-tie seat

* Re-design of areas that are subject to flow

* Reduce unwanted flow

* Allow frog to flow to desired shape or profile

* Maintain wheels to reduce or eliminate hollow treads.

Evaluation of frog running-surface profiles designed to promote a wide, centered contact band will be conducted at the Facility for Accelerated Service Testing.

The high-tonnage loop at FAST, with 39-kip wheel loads, provides researchers and railroads an accelerated test of track components and maintenance practices.