A4 difficulty slowing down
I have 3 A4 locos 2 I am using the other new and only run twice.
The two I use seem to accelerate OK but take a lot of clicks to slow down obviously after taking out the 5 clicks of backlash. The Mallad seemed to have particles of magnetic material on the motor magnet fouling the armature, these I cleared away finally with compressed air 90psi airline. The other just back from Hornby did not have the particles but I blew it with compressed air as well.
When closing the regulator it can take a lot of clicks and then the regulator closes suddenly and the loco jerks to a stop. Does this mean the regulator or the reversing mech is sticking. The motor seems more predictable in the opening mod than the closing mod. I use forward with the regulator pawl on the right hand side of the loco. I used to use it with it on the left side but when reversing loco still went forward until pawl on right for forward and pawl on left for reverse.
Has anyone else had this. Sometimes I have to click 12 times to stop the loco in addition to the backlash 5 clicks.
My A3 is predictable both up and down. One click down slows loco a bit. With A4 one click down no difference. Sometimes OK but often not.
My A3 has steam pouring out of the chimney on starting the first time after a few days in storage. It has new viton seals I fitted. Does this mean I need to change the pressure pad as I have one from the club. If I push the loco with regulator open with steam pouring out of the chimney it clears and the loco is OK for the rest of the steam and also if I steam again that day. I have changed the chimney seal a number of times and also the complete chimney screw and seal bought as a set.
I have now built a layout and run with DCC so I need more predictability from the control. The main problem with both A4s is the closing of the regulator in repeatable steps, each click closing a little.
With loco on rolling road and body off motor runs OK and also with body on motor can be heard to run OK.
Thanks Eric.
Cleaned/polished rotary valve with very fine grade wet and dry used dry as recommended by Maurice. A3 now runs smoothly and does not let steam out of the chimney when it warms up for the first time. Rotary valve had what looked like 3 circular score marks but these polished off and where really the deposits of burt oil and other material.
My other A4 erratic regulator response was caused by a build up of deposits similar to those in the A3 rotary valve. I polished with very fine wet and dry used dry and reassembled making sure the hole with the little tapered vee cut into it is opposite the whistle. The whistle hole is a simple straight hole the regulator steam hole in the one with the vee.
This A4 now works a treat. I did not oil the regulator due to the high superheater temperature.
All three of my locos now work OK. I checked magnets and clearance between magnets and armature on all three.