When slowing down in a Class 101 and the brake is in the lap position and I need to speed up a little can I speed up in the lap position or do I need to totally release the brake then speed up ??
Generally speaking, if you have the brake lever in the lap position that means you're keeping/holding the same amount of brake force in the pipes, so if you already have the brakes applied you'll effectively be dragging them along, which isn't exactly ideal. It's a good idea to have the lever in the off/released position if you plan to speed up.
So as above, lap position holds the current brake volume, if your volume is 0 then technically you can leave it in lap for faster applications of the brake.
Key to braking the Class 101 DMU. If your starting your braking some distance from station your stopping at have it in lap but only brake slightly say for example 45-50 % whilst it’s slowing position back to lap and then when required after you’ve slowed enough move to release but no need to fully release because you only braked 45-50 % or whatever. Wait until gauge reaches 21 and move back to lap ready to brake again. When you move to lap your last action whether braking or releasing will stay at that value. When more confident of braking performance and distance it’s possible to brake to stop very late by applying full braking or emergency but your passengers might not be pleased.