Abstract A pneumatically operated rapper including a piston reciprocable within a cylinder adapted to strike an anvil within said cylinder thereby imparting vibrations to a structure connected to said rapper, wherein the improvement comprises providing said piston and said cylinder of dissimilar materials of which one material possesses dry lubricating properties and one of said dissimilar materials is covered with a thin film of low friction material which is erodable by abrasion between said piston and said cylinder to form microscopic particles for coaction with said dry-lubricating material, thereby conditioning the coacting surfaces of the piston and cylinder for reduced friction and continuous dry-lubrication thereof.
In pneumatically operated apparatus including a piston rapidly reciprocable within a cylindrical housing to impart vibrations to a structure connected to said housing and wherein an outer annular surface of said piston is in rubbing engagement with an inner annular surface of said cylindrical housing, the improvement comprising: one of said annular surfaces comprising a first material having dry-lubricating particles therein and the other of said annular surfaces comprising a second material different from said first material; and a substantially thin coating of PTFE provided on one of said annular surfaces whereby the rubbing engagement resulting from reciprocation of said piston forms microscopic particles of said PTFE from said coating and releases microscopic particles of dry-lubricating particles from said first material for the mixing with said particles of PTFE for conditioning said annular surfaces for reduced friction.
Claim 2
Dependent Claim
137 words
In pneumatically operated apparatus including a piston rapidly reciprocable within a cylindrical housing to impart vibrations to a structure connected to said housing and wherein an outer annular surface of said piston is in rubbing engagement with an inner annular surface of said cylindrical housing, the improvement comprising: one of said annular surfaces comprising a first material having dry-lubricating particles therein and the other of said annular surfaces comprising a second material different from said first material; and a substantially thin coating of PTFE provided on one of said annular surfaces whereby the rubbing engagement resulting from reciprocation of said piston forms microscopic particles of said PTFE from said coating and releases microscopic particles of dry-lubricating particles from said first material for the mixing with said particles of PTFE for conditioning said annular surfaces for reduced friction.
Claim 3
Dependent Claim
17 words
The apparatus of claim 1 wherein said first material is ductile iron having nodules of graphite therein.
Claim 4
Dependent Claim
11 words
The apparatus of claim 2 wherein said second material is steel.
Claim 5
Dependent Claim
24 words
The apparatus of claim 3 wherein said PTFE coating comprises a coating of PTFE having a thickness of between .0006 inches and .0030 inches.
Claim 6
Dependent Claim
19 words
The apparatus of claim 4 wherein said inner annular surface has a rolled finish no coarser than 400 R.M.S.
Claim 7
Dependent Claim
18 words
The apparatus of claim 4 wherein said inner annular surface has a rolled finish at substantially 30 R.M.S.
Claim 8
Dependent Claim
16 words
The apparatus of claim 3 wherein said coating of PTFE is applied to said steel surface.