Dayton Die Cushions - Low Pressure Plumbing

Plumbing for low pressure die cushions (models C, D, MC and MD) 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 150 psi for low 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 regulator/gauge assembly) 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 tank is very important part of the die cushion system as it prevents the air to build up to prohibitive pressure at the bottom of the work cycle of the press. The larger the surge tank, the more constant ring holding force will be throughout the work cycle.

Surge tank is not required for model D die cushions with standard draws as they have enough internal surge volume. In this case only regulator and gauge assembly, pop safety valve and drain cock have to be installed. Pop safety valve should be mounted directly onto the die cushion into the tapped surge line hole. Drain cock should also be installed in the bottom of the piston to drain any accumulated moisture inside the die cushion. However, if longer than standard stroke is used on D style die cushions, surge tank must be installed for proper and safe operation of the die cushion.

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
C6 & D6	1/2	3/4	1 1/4	1 1/4	1 1/4	1 1/2
C8 & D8	1/2	3/4	1 1/4	1 1/4	1 1/4	1 1/2
C10 & D10	3/4	1 1/4	1 1/2	2	2	2
C12 & D12	3/4	1 1/4	1 1/2	2	2	2
C14 & D14	1	1 1/2	2	2 1/2	2 1/2	3
C16 & D16	1 1/4	2	2 1/2	3	3	X
C18	1 1/4	2	2 1/2	3	3	X
C20	1 1/4	2	2 1/2	3	3	X
C22	1 1/2	2 1/2	3	X	X	X
C24	1 1/2	2 1/2	3	X	X	X

Surge Port Size
Cushion Model & Size	Number of Cushions
Cushion Model & Size	1	2
MC8	3/4	1 1/4
MC10	1 1/4	2
MC12	1 1/4	2
MC14	1 1/2	2 1/2
MC16	2	2 1/2
MC18	2	3
MC20	2	3
MC22	2 1/2	4
MC24	2 1/2	4

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 125 psi	285	3/8 NPT
Pressure Gauge	284	1/4 NPT
Surge Drain Cock	443	1/4 NPT

Regulator and Gauge assembly regulates the shop air pressure and allows using die cushions at pressures lower than the shop air one. High pressure hoses should be used from the regulator to the cushion unit/cross when installing this assembly. A brass or steel pipe may be used, however, a high pressure hose is long-lived and absorbs the shock of the press on the regulator and gauge. Another hose should be used on the input side of the regulator to connect it to the shop air line that should be pipes within 2 to 2 1/2 feet of the pressure regulator. It is also advisable to install a globe valve and air filter on the end of the 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. The regulator and gauge assembly comes with a bracket and should be installed on the side of the press approximately 5-6 ft from the flow within easy reach and view of the operator.
After the globe valve has been attached to the shop air line, be sure to blow out the shop air line to remove any foreign matter or dirt before connecting the short length hose from the globe valve to the inlet side of the pressure regulator. If this precaution is not taken, there is a possibility that a small piece of dirt will get under the seat of the regulator valve and it will not function properly. Also, note that the regulator openings are marked with arrow to indicate direction of flow so that air hoses can be connected to the correct side for proper operation.

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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