This factory service manual covers the Gehl 721 and 721T (Telescopic) wheel loaders, and also documents the related 621, built on Manitou Americas models 303-00, 304-00, and 303-10. Publication 50940188, it runs 134 pages and is powered by the Perkins 1004-42 diesel engine.The manual is organized by system: maintenance, engine, the hydrostatic power train, axles, brakes, steering, the electrical system, and the work hydraulics. Each section carries specifications, tightening torques, diagrams, and inspection protocols.Owners and independent mechanics can use it to plan maintenance, set injection and valve figures, diagnose drive and transmission faults, adjust the brakes and steering sensors, and trace the hydraulic circuits. It is a downloadable PDF you can read on a device or print for the workshop, matched to the exact models and serial ranges the machine carries.
What's Inside This Gehl 721, 721T Manual
| System | Pages | Key Topics |
|---|---|---|
| Maintenance | 4-13 | Engine Fluids and Lubricants, Maintenance Kits, Maintenance Plan 621/721 (Model 303-00/304-00), Maintenance Plan 721 Telescopic (Model 303-10) |
| Engine | 14-29 | Engine: Overview, Safety, Specifications, Tightening Torques, Crankcase Breather, Fuel System |
| Power Train | 30-57 | Variable Displacement Motor – Overview, Solenoid Valve – Driving Direction, Hydraulic Circuit – Drive, Adjustment Work on Drive, Towing, Hydraulic Motor |
| Axles | 58-79 | Type Label – Axle, Rear Axle Tightening Torques, Planetary Drive, Differential Input Shaft, Planetary Carrier, Axle Tube and Differential, Gearbox Sealing Work |
| Brakes | 80-87 | Overview – Parking Brake, Brake Caliper – Adjustment, Service Brake, Brake Hydraulic Circuit, Brake Diagram, Service Brake – Component Parts |
| Steering | 88-93 | Overview – Steering Circuit, Steering Circuit, Steering Ram Front axle/rear Axle, Adjusting the Steering Sensors |
| Electrical System | 94-103 | Ohm's Law (Current, Voltage, Resistance); Power, Measuring Equipment, Measuring Methods, Terminal Description, Relay, Electrical Equipment, Electronics Box |
| Electrical Diagrams | 104-113 | Wiring Harness Engine And Frame, Wiring Harness – Cab, Wiring Diagram – Options |
| Hydraulic System | 114-134 | Control Valve Circuit – Loader Unit Model 303-00/304-00, Hydraulic Pump – Hydraulic Oil Tank Model 303-00/304-00 Circuit, Joystick – Control Valve Model 303-00/304-00 Circuit |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Standard tightening torques for screws and nuts (M10 x 1.50) | 44 Nm (4.5 kgf m) | p. 20 |
| Hydraulic oil filter insert replacement interval | every 12 months or 1200 service hours | p. 10 |
| Fuel filter (prefilter and main filter) replacement interval | every 50 service hours / weekly | p. 8 |
| Air filter insert replacement interval | every 3rd change of air filter insert and every 12 months or 1200 service hours | p. 8 |
| Flexible lines replacement interval | every 6 years (UVV, DIN 20066 T5) | p. 10 |
| Cylinder seal kits | Replacement indicated when damaged or during overhaul, specific clearance or torque values for the kits are not provided. | p. 67 |
| Drive belts | Condition and pretension to be checked, retightened or replaced if necessary. Specific values not provided. | p. 9 |
| Coolant hoses | Condition and pretension to be checked, retightened or replaced if necessary. Specific values not provided. | p. 9 |
| Battery specifications | 12 V/88 Ah (354x175x190 mm) | p. 100 |
| Forward high pressure at control piston when pressure suddenly drops (Control initiation on hydraulic motor) | approx. 290 – 300 bar | p. 39 |
| Engine oil capacity | 11 l | p. 6 |
| Hydraulic oil tank capacity | about 90 l | p. 6 |
Gehl 721, 721T Common Problems This Manual Covers
Loader will not travel under load
A loader that loses drive power or will not move often has a hydrostatic drive fault: low oil, a clogged filter, a solenoid valve issue, or pump and motor wear. The Power Train section covers the variable displacement motor, drive circuit, and a full inspection protocol.
Manual Section: Power Train p. 30Weak or slow hydraulic response
Slow or weak boom and bucket action usually comes from low fluid, a restricted filter, air in the system, or a control valve fault. The Hydraulic system section gives the control valve, pump, and joystick circuits to trace the loss.
Manual Section: Hydraulic system p. 114Engine overheats during work
Repeated overheating on the Perkins diesel points to the cooling system, thermostat, or coolant pump. The Engine section includes thermostat removal and checking plus the gear-driven coolant pump service.
Manual Section: Engine p. 14Steering is heavy or unresponsive
Heavy or erratic steering can stem from low pressure, a steering ram issue, or misadjusted sensors. The Steering section covers the steering circuit, front and rear axle rams, and adjusting the steering sensors.
Manual Section: Steering p. 88Weak or dragging brakes
Poor braking or a dragging parking brake usually needs caliper adjustment or service brake attention. The Brakes section provides the parking brake overview, caliper adjustment, and the brake hydraulic circuit.
Manual Section: Brakes p. 80Hydraulic oil leaks at hoses and fittings
Leaks from aging hoses and fittings are a routine service concern on these loaders. The Maintenance section lists the flexible line replacement interval and the filter and fluid service that keeps the system tight.
Manual Section: Maintenance p. 4Frequently Asked Questions
Which Gehl models does this manual cover?
It covers the Gehl 721 and 721T (Telescopic) wheel loaders and documents the related 621, built on models 303-00, 304-00, and 303-10, all powered by the Perkins 1004-42 diesel engine.
Where can I find the tightening torque specifications?
The Engine section lists the standard tightening torques for screws, nuts, stud bolts, and pipe connections, plus the special torque tensions, so you can set fasteners to factory figures. p. 14
Does it cover diagnosing drive and transmission faults?
Yes. The Power Train section includes an inspection protocol for the drive along with targeted checks such as the vehicle not reaching top speed, control or boost pressure not being reached, and jerky forward and reverse shifting. p. 30
Does it include hydraulic system diagrams?
Yes. The Hydraulic system section provides the control valve circuit for the loader unit, the hydraulic pump to oil tank circuit, and the joystick to control valve circuit for models 303-00 and 304-00. p. 114
What do I get after purchasing this Gehl 721, 721T manual?
A 134-page Service Manual in searchable PDF, ready the moment checkout completes. Open it on a computer, tablet, or phone with no shipping wait.
Am I able to print pages from this manual?
No restrictions at all. Print individual pages, full chapters, or the entire manual. The PDF is completely unlocked.
Are electrical wiring diagrams included in this Gehl 721, 721T Service Manual?
Yes, this Gehl 721, 721T Service Manual includes complete electrical wiring diagrams, wire routing, and connector pinouts.
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