Dayton Die Cushions - High Pressure Plumbing

Plumbing for high pressure die cushions (models HC, HD and HMC) includes the following components:
- Surge Tank with gauge, pop safety valve and drain cock
- Reducing Regulating Valve and Pressure Gauge
- System Drain Cock
All plumbing components used should be rated to the working air pressure of at least 300 psi for high pressure die cushions. Special attention should be given to make sure that plumbing is free of metal shavings and other debris (for example from threading pipes) that can get inside the die cushion piston-cylinder wall and destroy the bearing surface.
Die Cushion surge port is connected to the surge tank using pipe or hose assembly. At the convenient point outside the press bed, cross should be installed that gives additional two input/output points into the plumbing for shop air input line (through the booster pump) and system drain line.

When two or more cushions are installed in the same bed, they can be either tied into one air system or have independent air systems. Die cushions have to be under one air system if they have common pin pad or if the uniform system pressure has to be achieved between independent cushions.

If they have separate air systems, cushion pressures can be set differently thus achieving different tonnages. In such case general instructions for single cushion plumbing should be followed. As an option connecting line can be added in between surge tanks for each of the cushions with the ball valve. When the valve is closed each cushion will have different pressure, once opened valve will allow for uniform pressure in all of the cushions connected.

When multiple cushions are connected to one surge tank, the surge line size should increase as they join into one line (it is discussed later in this section).

Surge port is located either in the back or on the side of the die cushion piston flange. Depending on the installation, it can be also drilled in the bottom of the piston, if space inside the press bed is limited. All cushion units are drilled and tapped for the correct size surge line to handle the flow of air required. On multiple units installations a reducing bushing for the correct size is furnished to give the proper air flow for the entire installation. The pipe sizes given below are the recommended sizes for cushion installation consisting of one to six cushion units connected together.

Surge Port Size
Cushion Model & Size	Number of Cushions
Cushion Model & Size	1	2	3	4	5	6
HC8 & HD8	1/2	3/4	1 1/4	1 1/4	1 1/4	1 1/2
HC10 & HD10	3/4	1 1/4	1 1/2	2	2	2
HC12 & HD12	3/4	1 1/4	1 1/2	2	2	2
HC14 & HD14	1	1 1/2	2	2 1/2	2 1/2	3
HC16 & HD16	1 1/4	2	2 1/2	3	3	X
HC18	1 1/4	2	2 1/2	3	3	X
HC20	1 1/4	2	2 1/2	3	3	X
HC22	1 1/2	2 1/2	3	X	X	X
HC24	1 1/2	2 1/2	3	X	X	X

Surge tank should be installed as close to the cushion unit as possible to minimize the flow of air through surge lines. The surge tank itself may be installed in either a horizontal or vertical position as each surge tank has the required number of outlets to make either of the installations. Surge tank should have the pop safety valve, pressure gauge and drain cock installed. These components are furnished with each die cushion. For easy access, street elbow, nipple and coupling (1/4" NPT) can be installed on the bottom of the tank and then drain cock can be attached to them.

Description	Part Number	Connection
Pop Safety Valve 250 psi	6308	1/2 NPT
Pressure Gauge	6114	1/4 NPT
Surge Drain Cock	443	1/4 NPT

Booster pump intensifies input shop air pressure to achieve the maximum of 200 psi system pressure. The pump can be mounted horizontally or vertically to the press frame or any other convenient place by bolting through four holes provided in the mounting structure. Select space large enough to accommodate pump. If the pump is mounted on an uneven or curved surface, care should be taken not to bend pump. Booster pump should be connected to shop air line with standard pipe fittings (1/4" NPT) and to the cushion using high pressure hoses through the cross as shown below. It is also advisable to install a globe valve and air filter on the end of the shop air pipe so that air pressure can be turned off when cushion is not in use and only clean, free of debris air is delivered to the die cushion.

Description	Part Number	Connection Size
Regulator Assembly	1502	x
Regulator	3241	1/4 NPT
Pressure Gauge	284	1/4 NPT
Vibration Dampers	451	x
Hose Assembly	3248	x
3 ft Hose	6310	1/4"
6 ft Hose	6309	1/4"
Hose Adapters	6313	1/4" NPT
Globe Valve	Not Furnished	x
Air Filter	Not Furnished	x

System drain is important part of the die cushion plumbing. It allows removing all accumulated moisture inside the die cushion that can limit the surge volume and cause the increased system pressure (above allowable levels) at the bottom of the working stroke. That is why drain cocks should be opened regularly as a part of the die cushion maintenance schedule. Usually die cushion installation should have 2 drains installed, one at the low point of plumbing and the other one directly on the tank. To create the entry port for the second drain cock mentioned, cross and reducing bushing is shipped with die cushion. It should be installed outside the press so that there is easy access to the drain cock. The other open port on the cross should be used to connect high pressure hose from the regulator.

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