- Mini Hydraulic Excavator:
- 301.5 (S/N: 3YW4174-UP)
- 301.6 (S/N: BDH1022-UP)
- 301.6C (S/N: JBB1-678)
- 301.8 (S/N: BFA2883-UP)
- 301.8C (S/N: JSB1-1199)
- 302.5 (S/N: 4AZ5654-UP)
- 302.5C (S/N: GBB1-856)
Bucket cylinder drift may occur during the operation of a rotating grapple. Machines that are configured with a quick coupler for work tools and with secondary auxiliary lines experience the bucket cylinder drift. The bucket cylinder drift affects machines with a diverter valve at the head end of the bucket cylinder and without a diverter valve at the rod end of the bucket cylinder. The primary auxiliary lines rotate the grapple. The secondary auxiliary lines power the jaws.
Before connecting the secondary lines, the bucket cylinder should be fully retracted. The valve at the head end should be set to divert the flow to the secondary attachment. When the head end of the bucket cylinder is isolated, there is no load on the bucket cylinder when the grapple is hanging directly from the stick nose.
The use of a grapple with a quick coupler loads the bucket cylinder. The weight of the attachments cause the bucket cylinder drift when the secondary auxiliary circuit is operated. The spool opens on the rod end of the cylinder and flow is sent to the hydraulic tank.
The installation of an additional isolation valve in the hydraulic line for the rod end of the bucket cylinder prevents bucket cylinder drift. The isolation valves at the head end of the bucket cylinder and at the rod end of the bucket cylinder must be closed when the secondary auxiliary circuit is active.
Installation Of An Additional Isolation Valve
Use the information that follows in order to install an additional isolation valve.
Required Parts     | |||
---|---|---|---|
Item     | Qty     | Part Number     | Description     |
1 (1)     | 1     | 281-3948     | Hose As     |
1 (2)     | 1     | 287-3088     | Hose As     |
2     | 1     | 281-3949     | Bracket     |
3     | 1     | 129-3178     | Locknut     |
4     | 1     | 8T-4205     | Hard Washer     |
5     | 1     | 5C-9553     | Bolt     |
6     | 4     | 138-8454     | Screw     |
7     | 1     | 6V-8636     | Connector     |
8     | 2     | 6V-8397     | O-Ring Seal     |
9     | 2     | 3J-1907     | O-Ring Seal     |
10     | 1     | 268-1638     | Swivel Tee     |
11     | 1     | 156-5726     | Shutoff Valve     |
( 1 ) | Use With 301.6C And 301.8C |
( 2 ) | Use With 302.5C |
- Check the bracket on the left hand side of the stick. The bracket is for mounting the secondary auxiliary coupler. Drill hole (C) in the bracket, if the hole is not already present. Refer to Illustration 1.
Illustration 1 | g01281976 |
Bracket (A) 7.5 mm (0.3 inch) (B) 42.5 mm (1.7 inch) (C) 7 mm (0.28 inch) Diameter |
- Remove the existing hose and tee assembly from the connector on the rod end of the bucket cylinder.
- Install the replacement parts that are listed in Table 1. Refer to Illustration 2.
Illustration 2 | g01281980 |
Isolation Valve In The Secondary Auxiliary Circuit (D) Existing connector for the rod end of the bucket cylinder (E) Existing coupler assembly for the secondary auxiliary circuit |