This manual describes the DuraClass Model 1715, 1721, 1821, and 1824 HD single-acting, and Model 1715 DA, 1721 DA, 1821 DA, and 1824 DA-HD double-acting, twin-arm type hydraulic hoists. These hoists are designed for use with DuraClass steel dump bodies on single or tandem axled chassis, offering a dumping angle of 50° for all models. The manual provides comprehensive information on the design features, proper operation, and maintenance of these hoists.

Function Description:

The DuraClass hoists are hydraulic systems designed to raise and lower dump bodies for material discharge. The single-acting models utilize hydraulic pressure to extend the cylinder and raise the body, relying on gravity for lowering. The double-acting models use hydraulic pressure for both raising and lowering the body, providing more controlled movement in both directions. The twin-arm design ensures stability and strength during the dumping operation. The system integrates with the truck's power take-off (PTO) for hydraulic power, controlled from the cab.

Important Technical Specifications:

The hoist lifting capacities vary based on the model, body length, and mounting height. All capacities are based on mounting the body with a 12-inch (305 mm) overhang from the hinge to the end of the body, assuming level loading with the center of gravity at the midpoint of the body.

Model 1715 (Single-Acting):
- 8 ft body, 13-3/8 in mounting height: 12.0 U.S. tons (10.9 Metric tons)
- 9 ft body, 14-3/8 in mounting height: 10.5 U.S. tons (9.5 Metric tons)
- 10 ft body, 14-3/8 in mounting height: 9.0 U.S. tons (8.2 Metric tons)
Model 1721 (Single-Acting):
- 9 ft body, 14-3/8 in mounting height: 13.5 U.S. tons (12.2 Metric tons)
- 10 ft body, 14-3/8 in mounting height: 12.0 U.S. tons (10.9 Metric tons)
Model 1821 (Single-Acting):
- 9 ft body, 15-3/8 in mounting height: 17.0 U.S. tons (15.4 Metric tons)
- 10 ft body, 15-3/8 in mounting height: 15.0 U.S. tons (13.6 Metric tons)
- 11 ft body, 15-3/8 in mounting height: 13.0 U.S. tons (11.8 Metric tons)
- 12 ft body, 15-3/8 in mounting height: 12.0 U.S. tons (10.9 Metric tons)
Model 1824 HD (Single-Acting):
- 10 ft body, 16-3/8 in mounting height: 21.0 U.S. tons (19.0 Metric tons)
- 11 ft body, 16-3/8 in mounting height: 19.0 U.S. tons (17.2 Metric tons)
- 12 ft body, 16-3/8 in mounting height: 17.0 U.S. tons (15A Metric tons)
- 13 ft body, 16-3/8 in mounting height: 15.0 U.S. tons (13.6 Metric tons)
- 14 ft body, 16-3/8 in mounting height: 14.0 U.S. tons (12.7 Metric tons)
Model 1715 DA (Double-Acting):
- 8 ft body, 13-3/8 in mounting height: 12.0 U.S. tons (10.9 Metric tons)
- 9 ft body, 14-3/8 in mounting height: 10.5 U.S. tons (9.5 Metric tons)
- 10 ft body, 14-3/8 in mounting height: 9.0 U.S. tons (8.2 Metric tons)
Model 1721 DA (Double-Acting):
- 9 ft body, 14-3/8 in mounting height: 13.5 U.S. tons (12.2 Metric tons)
- 10 ft body, 14-3/8 in mounting height: 12.0 U.S. tons (10.9 Metric tons)
Model 1821 DA (Double-Acting):
- 9 ft body, 15-3/8 in mounting height: 17.0 U.S. tons (15.4 Metric tons)
- 10 ft body, 15-3/8 in mounting height: 15.0 U.S. tons (13.6 Metric tons)
- 11 ft body, 15-3/8 in mounting height: 13.0 U.S. tons (11.8 Metric tons)
Model 1824 DA-HD (Double-Acting):
- 10 ft body, 16-3/8 in mounting height: 21.0 U.S. tons (19.0 Metric tons)
- 11 ft body, 16-3/8 in mounting height: 19.0 U.S. tons (17.2 Metric tons)
- 12 ft body, 16-3/8 in mounting height: 17.0 U.S. tons (15.4 Metric tons)
- 13 ft body, 16-3/8 in mounting height: 15.0 U.S. tons (13.6 Metric tons)
- 14 ft body, 16-3/8 in mounting height: 14.0 U.S. tons (12.7 Metric tons)

Minimum required pressures for operation:

1715, 1721, 1821: 1000 psi (6 895 kPa)
1824 HD: 1500 psi (10 343 kPa)
1715 DA, 1721 DA, 1821 DA: 1300 psi (8 963 kPa)
1824 DA-HD: 1500 psi (10 343 kPa) Hydraulic systems require a minimum pressure of 3000 psi (20 684 kPa) for testing equipment.

Usage Features:

The hoists are operated via controls in the truck cab, which include a PTO handle (red) and a hoist handle (black) with a safety lock.

Engaging PTO (Manual Transmission): Place transmission in NEUTRAL, set hand brake, depress clutch pedal, shift PTO into gear, release clutch pedal.
Disengaging PTO (Manual Transmission): Depress clutch pedal, shift PTO out of gear, release clutch pedal.
Engaging PTO (Allison Transmission): Stop truck, set hand brake, with Allison transmission in a gear position for 45-60% engine speed PTO output, engage PTO. If gears don't mesh, creep truck slightly. After PTO engagement, move transmission to NEUTRAL.
Disengaging PTO (Allison Transmission): Move transmission shift lever into any gear position and shift PTO out of gear, then move transmission to NEUTRAL.
Hoist Operation (Optional Cable Control):
- Raise Body: With PTO engaged and engine running slightly above idle, release lever lock and move valve control to RAISE (rearward).
- Hold Body: Move valve control to HOLD. For extended holding, shift PTO out of gear and reengage lever lock.
- Lower Body: Release lever lock and move valve control to LOWER (forward). Once body rests on chassis, disengage PTO and reengage hoist control lever lock.

Safety Precautions:

Always read and understand the operation and maintenance manual before operating or servicing.
The hoist operating lever lockout must be engaged in the neutral position with the lever lock whenever the hoist is not in operation or the vehicle is in transit.
The PTO control must be in the OUT position when the vehicle is in motion.
Whenever the body is elevated, it must be securely propped or blocked to prevent it from falling. Both body props must always be used.
Do not exceed hoist capacities.
The vehicle must be on level ground before dumping.
Do not dump on recently excavated or uncompacted ground.
The operator must remain at the controls during the dumping cycle.
Tailgate controls must be released before the front of the body is 2 feet (0.6 m) above the chassis frame.
Keep personnel clear of the operating area and potential fall zones during operation.
When the truck is stored or not in use, the body must be in the full lowered position, resting on the chassis or hoist frame. The ignition key should be removed, and the cab locked to prevent tampering.
Disengage PTO when the hoist is not in use or when traveling on the highway. Do not move the truck (loaded or unloaded) unless the body is lowered and resting on the truck frame.
Never enter between a raised dump body and chassis frame as it may descend and cause injury or death.
In case of inoperative in-cab controls or failure to lower, follow specific emergency lowering procedures, including blocking the body with timbers, using a crane for controlled lowering, and ensuring all personnel are cleared from the area.

Maintenance Features:

Maintenance is divided into Preventive Maintenance and Corrective Maintenance (Troubleshooting).

Daily Maintenance:
- Inspect all caution and warning decals for legibility at the beginning of each shift. Clean or replace unreadable decals.
Weekly Maintenance – Lubrication:
- Lubricate the hoist at least once a week using the same grease recommended for the chassis. Apply oil to control rod ends, cable, cable levers, and link ends.
- Check hydraulic oil level:
  - Double-Acting Hoist: Extend cylinder to full stroke, block body, remove oil level plug from tank. Oil should be level with the plug opening. Add oil if necessary.
  - Single-Acting Hoist: Extend cylinder to full stroke, block body, remove vent fitting from top of cylinder. Oil should be level with the vent fitting opening. Add oil if necessary.
Monthly Maintenance Checks:
- Check bolt tightness at tie-downs, PTO, pump brackets, pump, cab controls, and (on double-acting models) control valve and hydraulic tank. Tighten as necessary. Replace self-locking nuts with equal parts if needed.
- Inspect the drive line for wear and check set screws for tightness and lock wire.
- Check and replace cotter pins in shaft ends.
- Check oil color for contamination. If thick or dirty, drain and replace.
- Check for oil leaks in hydraulic fittings and hoses. Retighten or replace as necessary.
- If equipped with an oil filter, change the element after the first month (approx. 50 hours), then refer to the six-month maintenance section.
6-Months Maintenance – Hydraulic Oil Change:
- Change system oil at least twice a year.
- Use hydraulic oil with an SAE 10W viscosity rating, containing antifoamant, rust and oxidation inhibitors, and an antiwear additive. If not available, use API engine oil, designation SE, with an SAE 10W rating.
- DO NOT use low viscosity naphtha base motor oil, hydraulic brake fluid, or aircraft hydraulic fluid.
- Change the oil filter routinely every half year (approx. 500 hours).
Corrective Maintenance (Troubleshooting):
- A trouble chart is provided to aid in diagnosing and correcting issues such as failure to raise load, oil foaming, and unsteady body movement.
- Cylinder Repair: Major repairs should be handled by a DuraClass Distributor. Field repairs are limited to packing replacement. When replacing packing rings, cut them diagonally and install them 90° apart on adjacent rings. Dip packing in oil before assembly. The packing nut should be snug, not tight, with a light film of oil on the rod.
- Pump Repair: Replacement parts are available, but pumps should be returned to a DuraClass Distributor for repairs beyond seals and O-rings.
- Control Valve Repair: Replacement parts are available, but valves should be returned to a DuraClass Distributor for repairs beyond seals and O-rings.
Maintenance Safety: Always ensure the body is securely propped or blocked when raised for repairs or adjustments. The HOIST control lever must be in neutral with the lever lockout engaged in the "lock" position, and the PTO disengaged. Use high-quality test equipment capable of withstanding 3000 psi (20 684 kPa) minimum pressure.

DURACLASS 1715 - Page 6

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