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Post by antharro on Jun 30, 2010 13:19:04 GMT
Something I've noticed on 67ts recently...
When leaving a station, the sound of the motors will gradually raise in pitch as the train accelerates - all normal. But, the motion of the train will start smoothly, then lurch, then carry on accelerating smoothly, then lurch, then possibly lurch again, then carry on accelerating. All the while, the motor sound will be smooth and linear, not reflecting the lurch-y-ness of the actual acceleration.
I wondered about wheelspin, but if you get wheelspin in your car, the engine revs will go up, then drop back down once you gain traction. I would've expected to hear the motors spin up faster for a moment if that was the case.
Any ideas?
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metman
Global Moderator
5056 05/12/1961-23/04/2012 RIP
Posts: 7,400
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Post by metman on Jun 30, 2010 21:59:34 GMT
I wonder if it is anything to do with the PCM? I've noticed it too.
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Post by plasmid on Jun 30, 2010 22:36:27 GMT
I remember the 67ts doing this all the time when I used to travel on the line as a child with my mum. Guess I just got used to it and never really paid attention to it!
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Post by t697 on Jun 30, 2010 22:43:06 GMT
Something I've noticed on 67ts recently... When leaving a station, the sound of the motors will gradually raise in pitch as the train accelerates - all normal. But, the motion of the train will start smoothly, then lurch, then carry on accelerating smoothly, then lurch, then possibly lurch again, then carry on accelerating. All the while, the motor sound will be smooth and linear, not reflecting the lurch-y-ness of the actual acceleration. I wondered about wheelspin, but if you get wheelspin in your car, the engine revs will go up, then drop back down once you gain traction. I would've expected to hear the motors spin up faster for a moment if that was the case. Any ideas? There's a few possibilities; 1. If you are leaving a station where there's points and crossings or a sub-station gap just outside the station, individual cars will stop motoring when their collectors shoes are 'gapped' then remotor when they reach conductor rails again. 2. A feature of 67TS and 72TS is that the tractive effort in first notch Parallel is quite low so as to give a smooth transition from series to parallel if the train is in the lower Rate 1 setting. Normally in Auto, Rate 2 is used so there is a little drop in acceleration after transition until the Parallel RPA takes a notch or two bringing the current back up to Rate 2 acceleration value. 3. The 67TS and 72TS were retrofitted in the 1980s with a simple motoring wheelspin control. If the wheels spin (low adhesion), the RPA notches back re-inserting resistance, lowering the motor current and hence the torque, until slip is corrected. Then it notches up again but in Rate 1. You can usually hear/feel the slip but the control and correction is quite good and you might not hear it happening if there's a lot of ambient noise or you are on a trailer car for example. |
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Jul 2, 2010 12:53:06 GMT
Something I've noticed on 67ts recently... When leaving a station, the sound of the motors will gradually raise in pitch as the train accelerates - all normal. But, the motion of the train will start smoothly, then lurch, then carry on accelerating smoothly, then lurch, then possibly lurch again, then carry on accelerating. All the while, the motor sound will be smooth and linear, not reflecting the lurch-y-ness of the actual acceleration. I wondered about wheelspin, but if you get wheelspin in your car, the engine revs will go up, then drop back down once you gain traction. I would've expected to hear the motors spin up faster for a moment if that was the case. Any ideas? There's a few possibilities; 1. If you are leaving a station where there's points and crossings or a sub-station gap just outside the station, individual cars will stop motoring when their collectors shoes are 'gapped' then remotor when they reach conductor rails again. 2. A feature of 67TS and 72TS is that the tractive effort in first notch Parallel is quite low so as to give a smooth transition from series to parallel if the train is in the lower Rate 1 setting. Normally in Auto, Rate 2 is used so there is a little drop in acceleration after transition until the Parallel RPA takes a notch or two bringing the current back up to Rate 2 acceleration value. 3. The 67TS and 72TS were retrofitted in the 1980s with a simple motoring wheelspin control. If the wheels spin (low adhesion), the RPA notches back re-inserting resistance, lowering the motor current and hence the torque, until slip is corrected. Then it notches up again but in Rate 1. You can usually hear/feel the slip but the control and correction is quite good and you might not hear it happening if there's a lot of ambient noise or you are on a trailer car for example. Would have thought your point 2 is what the original poster is experiencing. You can feel and hear the notching if not much background noise on the train. I'd be surprised if there is anywhere on the Vic that a 67 Stock can spin its wheels, unless there is a lubrication problem. |
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Post by t697 on Jul 27, 2010 20:42:39 GMT
I'd be surprised if there is anywhere on the Vic that a 67 Stock can spin its wheels, unless there is a lubrication problem. At the time we did the wheelspin control mod, there was quite a severe problem with out of adjustment track lubrication. The wheelspin control mod and better attention to lubricators did improve things and allowed re-instatement of virtually the original intended acceleration rate in ATO. |
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