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Patrick Pelgroms' Self Contained JYH - Belgium      VIDEO!

Self contained power hammer air schematic
At Start/Idle:
         Air is sucked in through check valve E and the ram is pumped up to the top cushion.
         Pressurized air above the ram leaks out at D (as adjusted).
         Air from top of pump is exhusted through B.
         Space in the top of the ram cylinder beyond the port acts as a cushion.

At Run:
         Top cylinder valve A opens to push cylinder down. Exhaust B closes.
         Top and bottom cylinders exchange air operating in unison.

At Mixed/Run:
         Valves A and B are partialy open. Hammer gives light and controlable blows.

At Stop:
         Manual valve on bottom line (not shown) is vented to drop ram to safe position.
         Valve can also act as compression release while motor is starting.

Check (one direction) Valves C,D and E:
         Spring or gravity closing similar in function but have different characters.
         C is a light action spring intake valve similar to compressor reed valves.
         D is an adjustable "pop-off" valve adjusted to low pressure controlling the pump up rate.
         E is a gravity or spring loaded "foot" valve that lets air into the bottom half.

Diagram by Jock Dempsey (c) 2007

self contained JYH
Hammer Page 1

Designed and built by
Patrick Pelgroms of

Streaming Hammer VIDEO!
Industrial Duty hammers exhuast and replace the air in the lower half of the system as well as the top. This prevents them from overheating the air and dieseling which can be destructive and dangerous.

Due to the air that is sucked back into the exhaust on this machine the exhust needs to be plumbed through an oil trap and a outdoor exhaust. The long pipe acts as a filter to prevent dirty shop air from being sucked into the hammer. Some industrial hammers intake and exhust air into their hollow frame.
Copyright © 2007 by Jock Dempsey, DEMPSEY'S FORGE