Spring and Equalization Parts

    Making the small parts of the locomotive springs and equalization system has proven time consuming and challenging.  It is becoming clear that part orientation on the printer is critical.  The set of five short trapeze levers above were printed with the sides vertical.  Yield of good parts built this way was very poor with just two parts being usable.

    The two parts in the above photo were good enough for use after minor trimming with a model knife.

    The short trapeze levers are about 1" long and have side bars only 0.030" thick.  The nearest side will have a clearance hole for a 1-72 machine screw while the opposite end with the larger round feature will be threaded for the 1-72 screw.  The top "T" shape slides into the slots on the top of the springs.  The lever connects the center four drivers to a hole in the frame anchoring one end of one of the equalizer strings.

     The other end of the springs connect to an intra-chassis lever that pivots within the brake hanger between  the Front and Intermediate drivers and another between the Main and Back drivers.  The lever connects equalization pressure to the neighboring spring via another long trapeze lever.  Above is a photo showing a poor yielding run that only netted two usable levers that need work to clean them up.  They are somewhat ragged though.

    By rotating the levers on the build platform a very good set of five levers was produced.

    The above photo shows the levers just after removal from the raft and supports.

     The levers are a bit over 1" long and came out very good with only minor cleanup needed.

    The small amounts of clear PLA that adhered to the levers was easily removed by prying them loose using a model knife.  Very little cleanup was required.

    The above photo shows a set of four riser and clamps on the raft and supports.  None of these were directly usable.   This run was done with clear PLA raft and supports where a previous run used green ABS raft and supports for black parts.  The previous run was all good, this one was all bad.  The combination of materials as well as the orientation is critical.

    The above photo shows a trial fit of the two trapeze levers, spring on riser and clamp and the intra-frame equalization lever.  The right hand long trapeze is located so as to connect to the spring of the driver forward of the Intermediate driver shown.  The screws used as pivots for the intra-chassis lever are 3-48 while the attachment screws for the trapeze levers to the intra-chassis lever are 1-72.   The spring and equalization portion assembled above works freely and flexes the spring when pressure is applied directly from the driver or via the long trapeze lever forward of the wheel.

    Another run of risers arranged sideways was more successful, most being good.

    Similarly, runs of short trapeze levers oriented sideways on the raft and support resulted in very good results.  It is more difficult to remove from the PLA support, but it does come away with careful use of needle nose pliers and finger pressure.  Flexing the support tends to release the black ABS part without too much residue.

     Above is a collection of good parts being accumulated to build and install the spring and equalization system on the frame.  At left is a stack of spring leaf sets to build the seven remaining spring sets.  The risers and clamps in the middle will provide part of the spring mounts, seven are needed so one extra is available if needed.  The three intra-chassis levers above complete the needed quantity.  They have already been drilled for the center 3-48 pivot screw and 1-72 trapeze attachment screws.  The short trapeze levers at the bottom need drilling and tapping to accept the 1-72 screws.  Only three short trapeze levers are still needed.

    Above a set of long trapeze levers still on the raft and support structure are added to the collection of parts.  Six long trapeze levers are needed to complete the ensemble of parts.

    The eight long trapeze levers above will need removal from the raft and support structure and then drilling and tapping for the 1-72 attachment screws.  With these parts enough are now available to fabricate the bulk of the spring and equalization system.  At each end of the chassis portion being built a cross lever is used to carry the equalization forces forward to the pilot truck and backwards to the trailing truck.  These levers will need design and fabrication to complete the system of levers for locomotive suspension equalization.