HWH 725 Series Computer-Controlled Leveling — Operation, Maintenance & Manual Retract

Overview

The HWH 725 Series is a computer-controlled BI-AXIS hydraulic leveling system with four straight-acting jacks that both power-extend and power-retract. A 12 V pump/manifold assembly feeds four jack solenoid valve pairs; a remote-mounted electronic sensing unit reads vehicle attitude and a multiplexed I/O module runs the show from a dash touch panel. Jacks always move in pairs: both front, both rear, left-front + left-rear, or right-front + right-rear. Because the jacks are straight-acting, the coach must never be moved with any jack extended or touching the ground — doing so damages jacks and chassis and is a driving hazard.

Touch panel in brief

AUTO LEVEL starts automatic leveling; AUTO STORE retracts all four jacks; CANCEL stops any operation. The four UP arrows extend jack pairs, the four DOWN arrows retract them. Four yellow lights show which side/end is low (all out = level); four red lights warn that a jack is extended roughly 1/4–1/2 in or more; EXCESS SLOPE means the system ran out of jack stroke; NOT IN PARK/BRAKE means the park-brake signal is missing; TRAVEL MODE (with ignition on, jacks stored, no red lights) is the ready-to-drive light. A separate master JACKS DOWN dash light plus buzzer sounds whenever a jack is down with the ignition on.

Automatic leveling

1. Park, set the transmission for parking, set the park brake, shut the engine off and turn the ignition to ACC. Place pads under the jacks on soft ground.
2. Press AUTO LEVEL once — the light flashes. On air-suspension coaches with HWH-controlled dump valves the suspension air dumps for about 25 seconds first.
3. The system extends jacks starting with a lit side light until all yellow lights are out, then stabilizes: any jack not used for leveling is driven to the ground until its jack pressure switch closes, lifting the coach roughly 1/4–3/4 in. The pump cycles on and off during this — normal.
4. If two jacks reach full stroke with a yellow light still lit, EXCESS SLOPE comes on and the sequence stops. Store the jacks and move to a flatter spot, or level manually as close as possible.

Retracting (STORE)

Start the engine, then press AUTO STORE. Front jacks begin retracting about five seconds before the rears. The pump keeps all retract valves energized until 10 seconds after the last red light goes out (or six minutes maximum). Do not interrupt power, press OFF, or turn the key while the STORE light is flashing. If a jack fails to retract, the system holds STORE mode for 50 minutes — see the manual retraction procedure below and get the system serviced. Verify visually that every jack is fully stored before driving; do not rely on lights alone.

Pump run-time limits

Pump motors come in 3 in, 3.7 in and 4.5 in diameters. Never run a 3 in motor more than three minutes, or a 3.7/4.5 in motor more than six minutes, without a 30-minute cool-down; the processor enforces a timer on most 725 systems, and the auxiliary pump-run toggle carries a 4-minute limit. Continuous running burns up the motor. The system operates down to 0 °F (slowly below freezing); below −20 °F it needs cold-weather synthetic oil — consult HWH.

Hydraulic fluid

Spec: HWH Specialty Hydraulic Oil. In an emergency, Dexron automatic transmission fluid is acceptable (it stains red if it leaks). Never use brake fluid or hydraulic jack fluid — either destroys the seals. Check the level with every jack, room and step fully retracted: fluid belongs within one inch of the top of the reservoir, between the grooves on the breather-cap dipstick. Overfilling pushes oil out the breather. Clean all debris off the reservoir top before opening the cap; the cap's dipstick end doubles as a 1/4 in nut driver for valve-release nuts. Check on delivery and at least every two years — more often if anything leaks.

Emergency manual jack retraction

WARNING: the coach starts dropping the instant a valve is opened. Keep everyone clear — the vehicle can drop and shift forward or backward without warning. Never crawl under the vehicle to reach the manifold; if there is no access from outside the frame, stop and call for service. Open release devices slowly.

1. Locate the pump/manifold assembly and identify the four jack solenoid valves (labelled LF, RF, LR, RR). Each valve has a manual release: a release cam, a 1/4 in release nut, or a T-handle. Old hex-bodied valves have no manual release.
2. Start at the front of the coach. Slowly open the left-front valve a partial turn, let the jack settle, close it; then the right-front the same way. Alternate left/right several times so the coach comes down evenly and the chassis does not twist.
3. With the weight off the front jacks, open both front valves fully until the jacks are retracted, then repeat the whole sequence at the rear.
4. Release types: cam release — the cam may be clocked in any direction on the valve, so check the OPEN/CLOSED arrows before pushing; forcing it the wrong way breaks the valve. 1/4 in nut release — remove the plastic plug and turn counter-clockwise, no more than 2 full turns on a 2-1/4 in valve or 4-1/2 turns on a 1-1/2 in valve. T-handle — about 4-1/2 turns counter-clockwise; it stiffens as the spring compresses.
5. Close every release (cam to CLOSED, nuts/T-handles snug clockwise — do not overtighten) once the jacks are up. The system must be inspected before the next use.

If the jacks are retracted but the pump is dead, the auxiliary hand pump (where fitted) can also power equipment: open the extend or retract solenoid valve for one function, stroke the two-stage pump (it "snaps" into its high-pressure stage under load), then close the valve. To prime a dry hand pump, open one extend and one retract valve of the same function, pump 8–10 strokes, close both and retry.

Routine care

Wash caked mud off the jacks but never wipe, oil, or spray the polished rods. After winter driving, rinse jacks with warm soapy water — road de-icers keep absorbing moisture and corrode them. Keep batteries strong (a healthy bank rests near 12.7 V; weak batteries cause erratic leveling), keep grounds clean and tight, inspect hoses and wiring for chafe, and confirm the NOT IN PARK/BRAKE interlock annually: with wheels chocked and park brake released, AUTO LEVEL must refuse to run and light the indicator.