neo67 Posted August 13 Share Posted August 13 Locomotive A4 just hums and does not move off. What could have happened? As can be seen in Pic1, the upper pivot point of the counter crank is far too high. Pic 2 shows the normal radius of the upper pivot point in the color red. How does this happen? The motor is apparently so strong that it pushes the counter crank upwards when the locomotive is blocked. In other words: If the locomotive is stuck somewhere, it pushes the counter crank upwards. How do I fix this for the moment? It's relatively simple: As you can see on the description of the locomotive, three screws must be removed to raise the body slightly, but not too far. Then turn the counter-crank back a little counter-clockwise with a lot of feeling to 6 p.m. as shown in Pic 2 and the locomotive will run again. The video shows, how it runs normally. But it will happen again next time, if the locomotive is stuck . There are already users in the Facebook group who leave the locomotive in the pack. How can you prevent this from happening again and again? Thanks & Greetz neo67 VID_20240813_094545.mp4 Link to comment Share on other sites More sharing options...
ntpntpntp Posted August 13 Share Posted August 13 I'd have thought it more likely that someone didn't check the position of that link when re-fitting the bodyshell previously. Link to comment Share on other sites More sharing options...
neo67 Posted August 13 Author Share Posted August 13 57 minutes ago, ntpntpntp said: I'd have thought it more likely that someone didn't check the position of that link when re-fitting the bodyshell previously. No, unfortunately not, this happens during the driving. Link to comment Share on other sites More sharing options...
Going Spare Posted August 13 Share Posted August 13 Mods: please move this thread to the TT sub-forum where it is far more likely to be read by TT users with potential solutions. 1 Link to comment Share on other sites More sharing options...
atom3624 Posted August 13 Share Posted August 13 This could have been during handling / carrying - easily done? Al. Link to comment Share on other sites More sharing options...
Silver Fox 17 Posted August 13 Share Posted August 13 2 hours ago, neo67 said: Locomotive A4 just hums and does not move off. What could have happened? As can be seen in Pic1, the upper pivot point of the counter crank is far too high. Pic 2 shows the normal radius of the upper pivot point in the color red. How does this happen? The motor is apparently so strong that it pushes the counter crank upwards when the locomotive is blocked. In other words: If the locomotive is stuck somewhere, it pushes the counter crank upwards. How do I fix this for the moment? It's relatively simple: As you can see on the description of the locomotive, three screws must be removed to raise the body slightly, but not too far. Then turn the counter-crank back a little counter-clockwise with a lot of feeling to 6 p.m. as shown in Pic 2 and the locomotive will run again. The video shows, how it runs normally. But it will happen again next time, if the locomotive is stuck . There are already users in the Facebook group who leave the locomotive in the pack. How can you prevent this from happening again and again? Thanks & Greetz neo67 VID_20240813_094545.mp4 With 25 A4's I have never encountered this once and not heard of it before so doubt it is a problem for many. Obviously yours is having problems so there could be an issue with your model which might need returning if it continues. Link to comment Share on other sites More sharing options...
Going Spare Posted August 13 Share Posted August 13 Others with this loco can shoot me down if I am wrong but the position of the lubricator drive crank on the rear wheel does not look to be in the right position because, during each revolution it does not push the rod far enough forwards to give an even motion of the crank at the lubricator. Assuming TT models use the same methods as their 00 equivalents, is the crank sitting correctly on the flats of the wheel crank pin or has the crank pin been inserted in to the wheel in the correct position (if that is possible)? 1 Link to comment Share on other sites More sharing options...
neo67 Posted August 13 Author Share Posted August 13 36 minutes ago, Silver Fox 17 said: With 25 A4's I have never encountered this once and not heard of it before so doubt it is a problem for many. Obviously yours is having problems so there could be an issue with your model which might need returning if it continues. This user (picture) came shortly after I posted this in the FB group. Sometimes certain margins are incorrect, for whatever reason. After all, it is assembled by people and they can make mistakes too ;) 20 minutes ago, Going Spare said: Others with this loco can shoot me down if I am wrong but the position of the lubricator drive crank on the rear wheel does not look to be in the right position because, during each revolution it does not push the rod far enough forwards to give an even motion of the crank at the lubricator. Assuming TT models use the same methods as their 00 equivalents, is the crank sitting correctly on the flats of the wheel crank pin or has the crank pin been inserted in to the wheel in the correct position (if that is possible)? I can't see any other way of putting this together. Unless the crank lengths were calculated incorrectly. 42 minutes ago, atom3624 said: This could have been during handling / carrying - easily done? Al. No, as I already wrote, this has now happened 3 times while driving. At an obstacle, a curve that was too tight and when starting off with 7 coaches. @all I have now pulled the crankpin out a little further (0.5mm) and it seems to be working better. I will keep an eye on it. Link to comment Share on other sites More sharing options...
What About The Bee Posted August 13 Share Posted August 13 Crank pins can be installed at an angle, not perpendicular to the surface of the wheel. This would cause binding in the rods. Which in turn can cause the motor to apply force without motion and therefore hum. So what Going Spare says could easily be a issue. The position of the return crank is critical. Going Spare notes that the strokes are uneven. They should be even. Ease the screw on the return crank, rotating it slightly, and gently nip up the screw. If the stroke is far enough out of true, you may get to a position where all the rods are in line, and thus, which way it goes is down to chance. How to check? Slowly rotate the wheels by hand. Gently wiggle the lubricator rod to see if it can invert when near straight. Just a thought Bee 1 Link to comment Share on other sites More sharing options...
atom3624 Posted August 13 Share Posted August 13 (edited) Not familiar with the fabrication of the TT120 locomotives, but I would remove the motor from it's 'mesh' and see how easy it is to roll / push along the track, and establish where any tight spots are - then follow the other considerations already mentioned. Al. Edited August 13 by atom3624 1 Link to comment Share on other sites More sharing options...
neo67 Posted August 13 Author Share Posted August 13 4 hours ago, What About The Bee said: The position of the return crank is critical. Going Spare notes that the strokes are uneven. They should be even. Ease the screw on the return crank, rotating it slightly, and gently nip up the screw. If the stroke is far enough out of true, you may get to a position where all the rods are in line, and thus, which way it goes is down to chance. How to check? Slowly rotate the wheels by hand. Gently wiggle the lubricator rod to see if it can invert when near straight. Just a thought Bee Hi Bee, is the return crank the red short one in the picture and what does @Going Spare means with "strokes are uneven"? Thanks Link to comment Share on other sites More sharing options...
What About The Bee Posted August 13 Share Posted August 13 12 minutes ago, neo67 said: The part you have highlighted in red is what I called the lubricator rod. The return crank is on the left, connected to it. This drives the pump rod, connected to the lubricator rod, on the right. Now in real life, the pump rod should just oscillate back and forth, with equal strokes on either side of the pump itself, here a black lump of plastic. The return crank drives the lubricator rod, as a function of wheel rotation. But if the return crank is not well adjusted, there can be too much stroke. Rotate that wheel about 180°. You will see that the return crank and the lubricator rod become almost in line. This is because the return crank is at an angle to the crank that drives the connecting rod. The return crank should go right back over the top of the wheel axle. From your image, I see it does not. It's about 15° out of phase and I suggest that this angle causes the extra stroke that Going Spare speaks of, and the alignment that I suggest may be happening. The return crank needs to be put back in phase Bee 1 Link to comment Share on other sites More sharing options...
Rog RJ Posted August 13 Share Posted August 13 When the loco first starts to move the centre driving wheel moves before the rear driver. Is one of the wheels loose on its axle? Link to comment Share on other sites More sharing options...
neo67 Posted August 13 Author Share Posted August 13 11 minutes ago, What About The Bee said: The part you have highlighted in red is what I called the lubricator rod. The return crank is on the left, connected to it. This drives the pump rod, connected to the lubricator rod, on the right. Now in real life, the pump rod should just oscillate back and forth, with equal strokes on either side of the pump itself, here a black lump of plastic. The return crank drives the lubricator rod, as a function of wheel rotation. But if the return crank is not well adjusted, there can be too much stroke. Rotate that wheel about 180°. You will see that the return crank and the lubricator rod become almost in line. This is because the return crank is at an angle to the crank that drives the connecting rod. The return crank should go right back over the top of the wheel axle. From your image, I see it does not. It's about 15° out of phase and I suggest that this angle causes the extra stroke that Going Spare speaks of, and the alignment that I suggest may be happening. The return crank needs to be put back in phase Bee I will try that. One question: Are the pins plugged in or screwed in? But not for another two weeks, tomorrow I'm going on vacation. Thanks for the constructive help @all, I'll stay tuned and report back. Thank you very much Greetz neo67 Link to comment Share on other sites More sharing options...
neo67 Posted August 13 Author Share Posted August 13 3 minutes ago, Rog RJ said: When the loco first starts to move the centre driving wheel moves before the rear driver. Is one of the wheels loose on its axle? You are right, I will test this! THX Rog! Link to comment Share on other sites More sharing options...
Rallymatt Posted August 13 Share Posted August 13 (edited) The rod for the lubricator is attached to the body where it will oscillate and to the rear axle by a slotted oval fixing. If the connection to the rear drive wheel is in the wrong phase you can get the issue you are experiencing, it can also do this if the slotted oval hole is not fitted correctly to the shaped drive pin but trapped by the fixing nut. The nut can be removed and check the state of the slot in the lubricator drive, a small file can remake the correct shape if needed, then orientate the lubricator rod correctly. In the factory a jig is used to set the linkage so it seems the most likely issue of incorrect setting after a post sale body removal. It is easy to correct 👍 Addition, the connecting rod pins are screwed in, there is a special tool from Hornby to remove and refix these easily, it’s called a ‘nut spinner’ and is in the shop, I think it might be listed under the track or accessory section Edited August 13 by Rallymatt 2 Link to comment Share on other sites More sharing options...
ntpntpntp Posted August 13 Share Posted August 13 20 minutes ago, Rog RJ said: When the loco first starts to move the centre driving wheel moves before the rear driver. Is one of the wheels loose on its axle? I think that's just due to the play in the rods and bearings. Mine is similar. I've always thought it's a shame Hornby didn't fit gears to all the driving wheels so the drive doesn't actually rely on the coupling rods. 1 Link to comment Share on other sites More sharing options...
Hobby11 Posted August 14 Share Posted August 14 I'm another where it just sits in the box, I got fed up with keep having to sort it, it's hardly noticeable anyhow. Link to comment Share on other sites More sharing options...
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