Hi,
... he worked as a greaser on the coal screens at Ystradgynlais ... I was wondering if anyone could give me some more information about this job ... I know he was not technically a miner but was I assume working on the surface? He was killed on the 3rd May 1935 when his clothes got caught in the screen ...
Many industries employed men to lubricate machinery of all sorts by adding oil and grease as necessary - they were often (but not always) termed 'greasers'. Unskilled work but necessary to keep machinery running and to minimise wear. Yes, it was surface work, not underground work.
In the inter-war years, coal screens, especially in the anthracite coalfield, were as much concerned with classifying the coal into the sizes demanded by the markets (peas, beans, nuts, cobbles, etc) as with removing waste stone and other non-coal material. Various size classifiying machinery was used; the simplest were large revolving drums made of steel mesh or steel sheet punched with holes - smaller pieces of coal fell through and larger pieces travelled further along until they reached holes of the right size to fall through; large coal emerged at the far end. The inter-war years saw a growth in markets for smaller sizes of coals (e.g. for automatically-fed boilers) so coal was often mechanically crushed at the start of the classifying process.
Crushing and moving coal produces lots of dust so part of a greaser's job was likely to be shovelling up the rapid build-up of dust and also spillages, as well as keeping vulnerable parts of the machinery (bearings, motors, etc.) moderately clean. Screens buildings, although often partly open-sided, were usually very dusty and, before modern standards of machinery guarding, potentially dangerous places to work - lots of moving machinery and poor visibility.
The local newspapers will have reported his death and also the resulting inquest. Runs of local newspapers are usually available at larger libraries and at county record offices. If the coroner's inquest records survive, they will most likely be held by the county record office.