STX-SERIES — MAINTENANCE
Checking Hydraulic Pressure
Many hydraulic problems are a result of low fluid levels. Before checking any other possibilities, make sure the hydraulic fluid level is up to the top of the sight glass which is located at the back/center of the frame.
Hydrostatic pressure can be checked using a pressure gauge with a range of at least 5,000 psi. Two male diagnostic quick couplers (one for each pump) are located beneath the right grill guard. To access couplers (Item B, Figure 26), remove the grill guard. It is best to use two gauges simultaneously (Figure 25), but it is possible to use only one gauge and repeat the procedure for each side.
To fully test the hydrostatic system, the spiders will need to be locked so that they cannot rotate.This can be done by wrapping a chain around an arm on each spider, thus chaining them together in the back of the trowel.
Once the pressure gauges are installed and the spiders chained together, the system can be checked.
With the foot pedal in the idle position and the engine at full speed, the pressure should be 200 to 300 psi. If the pressure is less than 200 psi, the charge system may need to be inspected and/ or serviced.In particular, the suction filter and charge pump relief valve should be checked.The suction filter may be plugged, or the relief valve may be stuck. Either condition may cause low charge pressure.
With the engine at 50% to 70% of full speed, and spiders chained together, slowly depress the foot pedal and read the gauges. The pressure should get to at least 4,350 psi (300 bar). If the pressure will not attain 4,350 psi (300 bar), the pump should be inspected and/or serviced by an authorized service representative.
2000 | 3000 |
PRESSURE GAUGE 5000 PSI RANGE
1000
150 200
100250
50300
bar psi
4000
5000
PRESSURE GAUGE 5000 PSI RANGE
WIKA
1000
2000 | 3000 |
150 200
100250
50300
bar psi
WIKA
4000
5000
RIGHT SIDE 
HYDROSTATIC PUMP
TEST PORT
| USE A PARKER HANNIFIN |
LEFT SIDE PUMP | QUICK DISCONNECT |
TEST PORT | |
| FEMALE COUPLER |
Figure 25. Pressure Gauge (Hydraulic Pump)
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