• SW-1500 Service Selector

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

  by KC8WJG
We have a 1969 ex-SP SW-1500. It has a service selector with four settings:

Switching 1
Switching 2
Series (Forestalling)

The only two we have ever used are switching 1 and road. I briefly put it in switching 2 for a few seconds and if I remember right, it started loading with the throttle in the idle postition. What is the difference between switching 1 and 2? And what would the series/forestalling position be used for. I understand that this switch basically controls the transition phases of the motors, but would like someone to clarify exactly what modes the unit is in in each of these positions.

Also, while I'm at it, another question. This unit of ours is leased from LTE Rail and has no alarm bells and doesn't appear to have any low water or crankcase buttons. Is this normal for this model or am I not looking in the right spots?

  by txbritt
Road loads the locomotive through the load regulator, slowly

Switching 1 bypasses the load regulator, so you get almost instant load

Switching 2 is the same as the above, except the engine is idled up to notch 3 rpm. So when you come out of idle notch, in effect you're coming straight into notch 3 without the delay in engine rev. I would use this position when we were kicking alot of cars. The engine noise gets overbearing after a little while if you're not using hearing protection.

Series/forstalling I believe is the same as Series hold? I never used this position.

As far as the low water button, If I recall on all the ECRX lease engines (ECRX 222-225) the buttons were located near the starter switch, on the fireman's side at the front.

Hope it helps,


  by KC8WJG
Thanks TXbritt for your response. I knew one of those postions by-passed the load regulator, just couldn't remember which one.

As far as the alarms go, I shouldn't have said that the unit doesn't have them since there is a bell present inside the high voltage cabinet in the cab -- I've just never heard it go off in the 13 months we've operated it.

This unit suffered a severe water leak last week and it was only detected when my helper and I were talking about our next moves while standing near the unit, and we saw water dripping from the carbody.

Makes we wonder if we hadn't have seen it, if there would have been an alarm bell, or if the engine would have kicked the low water button, wherever it is located.

  by Engineer Spike
The series motor connection is the 1st stage of transition. It gives lots of amps at low speed. This position would be used to haul long heavy cuts, at low speed. On CP, we have 2 classes of GP9s. The first class is for road service. They have d/b, and transition. The second class, for switching has no d/b, and the transition is in series. These units are limited to 30 mph under power. My former trainmaster was from the mechanical dept.,and he said that this was for heavy low speed pulling.

  by KC8WJG
Good info, thanks again gentlemen!

  by teddyted217
wow im late on this but just wanted to let you know i deal with a lot of older 1500's. There are some models that do not have engine protectors. Also if the engine has a alarm bell but it dose not ring then You probably have a bad bell or connection to the bell.

  by Engineer Spike
Sometimes the bell does not work because there was a problem. Rather than fixing it, they stuck a match book cover in it! To edit my post, I do not put the match book covers in the bell, but have found some there.
Last edited by Engineer Spike on Wed Dec 24, 2008 3:05 am, edited 1 time in total.

  by Aji-tater
Who does your 92-day inspections? One of the things required is a test of various alarms, shut-downs etc. If the bell has not worked for 13 months, it sounds like somebody is doing the inspection using a pen only. And the matchbook cover in the bell on Spike's engine would be deep $**t for whoever did it if the FRA could prove it.

  by rrboomer
I believe the purpose of series/forestalling is to keep trailing units in the consist (like SW-1200's) from making forward transition. However the forestalling position will not keep a road unit (SD-40-2, etc) from transition.

The low water and CCOP buttons should be right under the layshaft
  by WVU
The SW1500's that I work on, the traction motors are in series. This is for high current. The form of transistion that they make is called Field Shunting. These units do not change to Parallel. They make two steps of Field Shunting. They have a FSR1 and a FSR2 voltage over current relays in them, when these relay pickup, they bump the FSD relay (Field Shunt Delay Relay) and the FS1 and FS2 relay which looks like a selfload contactor will pick up and insert extra resistance into the Fields of the Traction Motors to counter the counter EMF that is bucking the feed of the D32 down to the traction motors. This will happen in the area of 20 to 22 mph.