QUOTE (Graham Plowman @ 30 Dec 2020, 02:16)
<{POST_SNAPBACK}>I have the same problem of jerky starts and jerky low speed with the Dapol class 22 Diesel Hydraulic. Strange thing is that it does this both on vanilla DC (with blanking plate and no decoder) and DCC (ESU Loksound 5) and it is worse in one direction than the other. Clearly a mechanical issue, not electronic. Have even replaced the motor with a new one and it made no difference. I suspect that the problem is a combination of the gear ratio being too high and the motor not being physically capable of running slow enough without jerking.
Kinda puts me off buying any other Dapol 00 locos as this isn't the first loco of theirs I have had with the same problem.
I was concerned about Dapol's inconsistency in 'centre motor both bogies driven' mechanism performance, ahead of my class 21 purchase. The only previous example of their work that I get to see regularly is an LMS 10000 owned by a friend; that performs admirably in all respects, silent, smooth from a dead slow creep, ample traction, and the on line reports were consistently favourable. Against that, reports of the 22 and 52 were 'mixed'. From what I have read reported a major problem is the pick up off the split axles, and modification to wiper pick up has made good out of poor runners; there may be further problems but not enough evidence to identify other 'definites'.
The running of my one example of their 21 is all it should be: immediately mechanically 'perfect' on a resistance controller, very refined indeed on DCC, and the general reception this model has received so far indicates it is pretty much trouble free. (The only significant criticism I have in respect of the class 21/29 mechanism is 'where's the assembly and parts diagram?'.) I'll be watching for any drop off in performance and should it happen this model will receive a wiper pick up mod.
Dapol's B4 0-4-0T is well regarded for mechanism performance, and I have seen one on an exhibition layout performing admirably, so the poor (too small) gear ratio choice on the 43xx is a surprise. The reports of the 43xx from those that operate their models are sufficiently unanimous that I regard this as fact, even though no one yet appears to have reported what the gear ratio is, nor the gear train layout! (If I had one and it exhibited the scale 5mph minimum crawl speed and way excessive maximum speed , it would be in pieces to see if the gear train has been misassembled. This is always possible if there is one or more intermediate stage between the pinion and the axle gear. Unfortunately GWR enthusiasts appear to be consistently devoid of any mechanical insight...)