Bachmann Spectrum Gear Replacement

PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
24,008
673
Tamworth, Staffs.
So..........

Has anybody tried to source a single-lead worm to fit? - That would slow it down, but might exacerbate any surging? :think:
 
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
25,762
756
North West Norfolk
So..........

Has anybody tried to source a single-lead worm to fit? - That would slow it down, but might exacerbate any surging? :think:
'twould be easier to replace the gearbox I suspect.

I've always had in mind that if the Centennial gear gives up, I'll substitute the gearbox, although that may be easier said than done as the whole things fits rather tightly , that's a sound way for a manufacturer to ensure that the gearbox stays in place. It's only us scratchbuilders who have to worry about anchoring a gearbox :smoke::smoke::smoke:
 
Greg Elmassian

Greg Elmassian

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8 Mar 2014
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Ah, gotcha - that makes sense - hence the higher gear ratios

Now I understand :nod::nod:
Actually, the ratio is lower numerically... more like 1:15 as opposed to something more desireable like 1:30.

My Bachmann expert just called on the phone as I am typing!

Based on the input from Barry Olson, Bachmann intended to make 1:30, and the prototype came from China as such. But someone else at Bachmann wanted a loco where you could push the loco and the drivers would turn, and China had missed that specification.

So China added a double lead worm as requested, but no one thought and realized that changing from a single lead to a double lead effectively changes the gear ratio by a factor of 2.

Internal screwup, these locos never ran over about 35 miles per hour, the double lead Bachmann will go over 60 miles per hour.

Greg
 
maxi-model

maxi-model

UK/US/ROW steam narrow gauge railways 1:1
27 Oct 2009
4,659
198
Bucks/Oxon/Northants area
But someone else at Bachmann wanted a loco where you could push the loco and the drivers would turn, and China had missed that specification.
That's always intrigued me about this loco. Why would anyone want to spec' a loco with this feature ? Apart from the obvious - it's quite handy when you want to "stage" the loco. It does not appear on any of my other Bachmann made products. It's also "fun" that you suddenly realise you now have an FOC generator on board to light up the head and classification lamps. Great little push along toy feature for all us big kids :D Max
 
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
25,762
756
North West Norfolk
Actually, the ratio is lower numerically... more like 1:15 as opposed to something more desireable like 1:30.

My Bachmann expert just called on the phone as I am typing!

Based on the input from Barry Olson, Bachmann intended to make 1:30, and the prototype came from China as such. But someone else at Bachmann wanted a loco where you could push the loco and the drivers would turn, and China had missed that specification.

So China added a double lead worm as requested, but no one thought and realized that changing from a single lead to a double lead effectively changes the gear ratio by a factor of 2.

Internal screwup, these locos never ran over about 35 miles per hour, the double lead Bachmann will go over 60 miles per hour.

Greg
Yes, another bit of English confusion - the lower the number of teeth the higher the speed - my phraseology is probably due to my thinking in terms of car gears.

Interesting bit about the horlicks - I knew that the K27s models were capable of a bit of overrun; they also have a flywheel on the motor. All this is good, as it means less stress on the gearbox.

All you've got to do then is get the ratios right :D:D
 
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
25,762
756
North West Norfolk
That's always intrigued me about this loco. Why would anyone want to spec' a loco with this feature ? Apart from the obvious - it's quite handy when you want to "stage" the loco. It does not appear on any of my other Bachmann made products. It's also "fun" that you suddenly realise you now have an FOC generator on board to light up the head and classification lamps. Great little push along toy feature for all us big kids :D Max
Well, there is also this thing about inertia control - with DCC and some R/C you can programme it in, so that you have to drive the train as if it has a few 100 tons of weight behind it. I remember using an R/C demo unit with inertia, and trying to get the train to stop at the platform - good fun for a while :smoke::smoke::smoke:
 
P

Paradise

Registered
28 Jan 2010
708
81
I thought it would be expressed as 30:1 or 15:1 whatever the case may be. The gears are there to reduce the revolutions from the electric motor whilst increasing torque.
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
24,008
673
Tamworth, Staffs.
Well, it has certainly increased the talk on this thread! o_O :think: :giggle:
 
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
25,762
756
North West Norfolk
I thought it would be expressed as 30:1 or 15:1 whatever the case may be. The gears are there to reduce the revolutions from the electric motor whilst increasing torque.
You may be right - I've certainly bought model gearboxes at 40:1 etc.

Most of the time, we know what we're talking about, but then sometimes ............... :lipssealed::lipssealed:
 
JimmyB

JimmyB

Phase 1 complete, roll on Phase 2
23 Feb 2018
2,088
338
65
Weston-super-Mare
So if it is motor to axle, with the worm gear on the motor shaft, 30 (or 15) rotations of the motor to one rotation of the axle ergo 30 (15) :1 is correct.
 
Greg Elmassian

Greg Elmassian

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I figured the order of the numbers whether motor to wheels or wheels to motor would be pretty moot, if the motor speed was increased 15 or 20 times, the top speed would be good enough for an aeroplane.

In any case, I don't like the double leads, so people will say that they coast nicely, that is true, but try stopping or even slowing a train on a grade, runaway! BEMF is not going to stop that train, ask me how I know!

Greg
 
Rhinochugger

Rhinochugger

Retired Oik
27 Oct 2009
25,762
756
North West Norfolk
I figured the order of the numbers whether motor to wheels or wheels to motor would be pretty moot, if the motor speed was increased 15 or 20 times, the top speed would be good enough for an aeroplane.

In any case, I don't like the double leads, so people will say that they coast nicely, that is true, but try stopping or even slowing a train on a grade, runaway! BEMF is not going to stop that train, ask me how I know!

Greg
Yep, you can only please some of the people some of the time :emo::emo:

Probably part of Bachmann's trouble - they listened to too many people. There comes a time when you have to stick to the plan :nod::nod:
 
P

Paradise

Registered
28 Jan 2010
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81
I just received an e-mail today stating that NWSL are now open for business which is welcome news. NorthWest Short Line
The website is still without images etc. and I can't find the gears for Large Scale.
Below is the Large Scale part of their replacement gears from the PDF on their old website.
I hope this helps with ordering from them if they still supply these items. As said before, it is best to count the teeth on the gear you need rather than going by their description for the 4-4-0 (or 2-6-0) which can be misleading.

137602_dda6d0c377e569718d52b72ab51d4bf2.jpg
 
Greg Elmassian

Greg Elmassian

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Yep, their web site came online a few weeks ago, but most of the G scale stuff was missing then, looks like the situation has not improved.

Many items were made to order, by hand, on non-automated machinery. I would guess demand has to drive inventory.

Greg