Dawson HPH 1200, User Manual

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4.3 Planned 250 hour maintenance checks (run the hammer for 15 minutes before and after
this maintenance work)
Every 250 hours the following work should be carried out in addition to the work described in 4.1
and 4.2 above:
a. Check the accumulator (part 1-048-00-04) precharge pressures using the gas pressure checking
kit and a bottle of nitrogen gas. The high pressure accumulator is situated on the side of the
hammer that the supply hoses come in.
The precharge pressures are:-
High pressure -100 bar
Low pressure - 3 bar
To gain access to the accumulators it is necessary to remove the top cover (part 1-017-00-02.)
To check the precharge pressures see appendix 7.2 in this manual.
b. Check the hammer filter (part 1-079-00-02) for cleanliness. First remove the top cover (part
1-017-00-02.) Then unscrew the filter bowl and remove the filter element. Check the filter for
damage and any unusual debris. Wash the filter with clean diesel and blast through from inside
the filter with compressed air. Alternatively throw the element away if it is a non-metallic filter.
PAY EXTRA CARE NOT TO ALLOW DIRT INTO THE FILTER ASSEMBLY ON
RE-FITTING
c. Check the function and condition of the bottom trip device.
d. Check the function of the hammer’s overtravel valve by intentionally overstroking the hammer
when cold.
4.4 Planned 500 hour maintenance checks (run the hammer for 30 minutes before and after
this maintenance work)
Besides work mentioned in 4.1, 4.2 and 4.3 above the following work should be carried out:-
4.4.1 Change the Resilient Washers
The flexible coupling between the main hydraulic ram and the drop weight must be changed. The
procedure is quite straightforward (see figure 5). Failure to do this will result in an expensive repair.
a. Lay the hammer on stable level ground on its Front Leg Guide packed on timbers. Remove the
Rear Leg Guide (part 1-002-00-02).
b. Remove the 3 no. Nyloc Nuts, Dog Point Grub Screws and Anti-Vibration Washers (parts
1-334-00-01, 1-349-00-01 and 2-089-00-01) from the Connector Nut (part 1-011-00-02). It may
require a little heat to melt the Loctite on the grub screws.
c. Unscrew the Connector Nut from the Ram Connector (part 1-009-00-02) and remove the Nut
together with 2 no. Buffer Spacers (part 1-012-00-02) and the Resilient Washer 2 (part
1-016-00-02).