Pennsylvania Trolley Museum's 1942 Porter centercab diesel uses a two stage engine start switch made by Leece-Neville. There is an 8 volt tap on the 32 volt battery. The first stage of the switch connects that low voltage tap to the starter solenoid. This gently engages the starter pinion into the ring gear. The second stage of the switch connects full battery voltage to the solenoid and starter to crank the engine. Our problem is that on both ends of the loco that low voltage contact in the switch has failed. This causes the starter to engage at full voltage, which is not a good idea. The switch is L-N number 132-SN-24-32V. If you have any info on this switch, or any spares of them, we'd sure like to know about it. We'll likely have to make new parts, given the age of the thing, but it would be good to know what's inside before we dismantle them.

David,
Perhaps a better forum for this question may be here:http://news.prestolite.com/forum. There is a forum for obsolete parts, some of the control products were also sold off to Ametek.
Prestolite is the successor to Leece-Neville. Does the switch actually handle the starter motor current or is there another relay involved?

Mike Tillger

The switch controls two things. On its first contact, made as the rotary handle is moved to the first position (non-detented, BTW) that contact connects the 8V tap of the 32V battery to the starter motor itself, but not to the starter solenoid coil. That is supposed to allow the starter a soft start, enough to spin it up and engage its Bendix drive pinion into the engine flywheel. When the switch is turned to the second position that contact puts full 32V battery current on both the solenoid coil and the starter itself, which cranks the engine. At that time the starter should already be engaged, and not arrive at the flywheel teeth with a bang.

I'll have a look at the Prestolite info, thanks for the lead.