The high impact force generated by the Allied Hy-Ram is produced from two sources. As much as 75% of the hammer's impact energy is derived from the compressed nitrogen charge above the percussion piston, while the hydraulic oil pressure from the carrier provides the remaining energy.
The nitrogen gas is affected by changes in temperature and the pressure will increase as the hammer reaches operating temperature. When checking pre-charge pressure refer to the table below. The pre-charge gas pressure is given in values for both 'hot' and 'cold' conditions.
NOTE: When checking pre-charge pressure, the hammer tool must always be fully extended so the percussion piston is at its' lowest most position.
Refer to the individual Hy-Ram model's technical manual for complete instructions on proper checking and charging of the hammer. Where the charge pressure listed in the manual differs from the pressure value in the table below, the manual will be updated to reflect this most current information.
Allied provides a nitrogen pre-charge kit with each new Allied hammer for checking/charging pressure. Additional kits are available by ordering the following:
|
Pre-Charge Pressure Specification by Hammer Temperature
Specifications listed in PSI & (BAR)
IMPORTANT: Use Nitrogen Gas Only! |
Hy-Ram
Model |
150º F* |
90º F |
70º F** |
50º F |
30º F |
| 99 |
60 (4.1) |
53 (3.7) |
50 (3.4) |
48 (3.3) |
45 (3.1) |
| 690 |
290 (20.0) |
260 (18.0) |
250 (17.2) |
240 (16.5) |
230 (15.9) |
| 700 |
175 (12.0) |
156 (10.7) |
150 (10.3) |
144 (9.9) |
138 (9.5) |
| 700B |
270 (18.5) |
242 (16.7) |
233 (16.0) |
223 (15.4) |
214 (14.8) |
| 710, 710B |
175 (12.0) |
156 (10.7) |
150 (10.3) |
144 (9.9) |
138 (9.5) |
| 711, 711B |
175 (12.0) |
156 (10.7) |
150 (10.3) |
144 (9.9) |
138 (9.5) |
715, 715B
(s/n 463-) |
215 (15.0) |
192 (13.2) |
185 (12.7) |
177 (12.2) |
170 (11.7) |
715, 715B
(s/n 463+) |
230 (16.0) |
206 (14.2) |
198 (13.6) |
190 (13.1) |
182 (12.5) |
| 725, 725B |
250 (17.5) |
224 (15.4) |
215 (15.0) |
207 (14.3) |
198 (13.7) |
| 730 |
180 (12.4) |
161 (11.1) |
154 (10.6) |
148 (10.2) |
142 (9.8) |
| 735CS |
175 (12.0) |
156 (10.7) |
150 (10.3) |
144 (9.9) |
138 (9.5) |
| 740, 740CS |
165 (11.4) |
147 (10.0) |
141 (9.7) |
136 (9.4) |
130 (9.0) |
| 745, 745CS |
195 (13.5) |
174 (12.0) |
168 (11.6) |
161 (11.1) |
154 (10.6) |
| 750, 750CS, 750B |
100 (7.0) |
89 (6.1) |
85 (5.9) |
81 (5.6) |
77 (5.3) |
| 755CS, 755B |
190 (13.0) |
170 (11.7) |
163 (11.2) |
156 (10.7) |
150 (10.3) |
| 770, 770CS, 770B |
120 (8.2) |
107 (7.4) |
102 (7.0) |
96 (6.8) |
94 (6.5) |
| 775CS, 775B |
180 (12.4) |
161 (11.1) |
154 (10.6) |
148 (10.2) |
142 (9.8) |
| 780, 780CS |
235 (16.2) |
210 (14.5) |
202 (13.9) |
194 (13.4) |
186 (12.8) |
| 785CS |
225 (15.5) |
201 (13.9) |
194 (13.4) |
186 (12.8) |
178 (12.3) |
| 790 |
165 (11.4) |
147 (10.0) |
141 (9.7) |
136 (9.4) |
130 (9.0) |
| 795CS |
200 (14.0) |
179 (12.3) |
172 (11.8) |
165 (11.4) |
158 (10.9) |
| 797CS, 797B |
230 (16.0) |
206 (14.2) |
198 (13.6) |
190 (13.1) |
182 (12.5) |
| 800 |
175 (12.0) |
156 (10.7) |
150 (10.3) |
144 (9.9) |
138 (9.5) |
| 805CS, 805B |
165 (11.4) |
147 (10.0) |
141 (9.7) |
136 (9.4) |
130 (9.0) |
| 905CS, 905B |
165 (11.4) |
147 (10.0) |
141 (9.7) |
136 (9.4) |
130 (9.0) |
* Standard operating or "hot" specification. ** Standard "cold" specification.
Values shown are with no contact pressure applied on tool. Tolerance of +0 / -5% psi is acceptable. Refer to the Hy-Ram Operator’s Manual for proper filling procedure. Pre-Charge kit, part number 657341, is required for filling and testing nitrogen gas pressure.
