Built for the 621, 721, and 721T Wheel Loader, this Service Manual (OEM #50940188) keeps your machine at factory spec across 134 pages. Hydraulic schematics map the full drive circuit, control valve routing, and joystick-to-valve connections for both loader and telescopic builds. Wiring diagrams carry cable colour coding, relay terminal descriptions, and fuse box layouts for cab and engine compartment. Power train troubleshooting alone runs 13 pages, working through jerky shifting, insufficient traction force, and failed motor control in second speed. Torque the M10x1.50 fasteners to 44 Nm; swap the hydraulic oil filter at the 1,200-hour mark. Both numbers come straight from the factory, not a forum thread. When the machine is down, you want the right figure once. Bookmarked by section and searchable by keyword, it opens on any device and takes you to the fault.
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 | - |
| 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
Gehl 721 loses drive power and won't travel under load, hydrostatic system unresponsive p. 50
Check boost pressure first; minimum is 30-32 bar (page 42). If pressure is short, inspect the hydraulic oil level (tank holds approximately 90 l) and pull the suction/reflux filter for blockage. Work the 'Boost pressure is not reached' steps on page 45. If boost is good but traction stays weak, continue with the 'Traction force insufficient' procedure on page 50.
Manual Section: Traction force insufficientHydraulic functions slow down across all implements, lift and curl noticeably weak at full throttle p. 114
Start with the hydraulic oil level; the tank holds approximately 90 l and low fluid is the most common cause. Replace the hydraulic oil filter insert if it has passed the 1,200-hour or annual interval (page 10). Inspect the suction filter for clogging and look for air entry points. Trace the control valve circuit in section 30300S10En_36, starting on page 114.
Manual Section: 30300S10En_36Engine turns over slowly or won't crank, no charging indication on dash instruments p. 28
Test battery voltage and terminal condition; the specified battery is 12 V/88 Ah (page 100). Clean corroded terminals and load-test. If the engine cranks but won't fire, inspect the fuel system and replace the fuel filter per the maintenance schedule on page 8. Work through the alternator steps on page 28 if the charging lamp is off or flickering.
Manual Section: Alternator TroubleshootingMachine lurches hard when shifting forward to reverse, drive feels rough at low groundspeed p. 53
Inspect the solenoid valve current supply and check the spool in the directional valve for sticking. Follow the 'Jerky shifting forward/reverse' procedure on page 53, which covers the drive direction switch, directional valve spool, solenoid current, and motor control initiation in sequence. Confirm boost pressure meets the 30-32 bar minimum (page 42) before any mechanical adjustments.
Manual Section: Jerky shifting forward/reverseSteering requires heavy effort to turn, wheel resists movement from center in both directions p. 93
Verify hydraulic oil level and inspect the steering circuit for leaks at the rams on both axles. Check sensor alignment using the procedure on page 93; a misaligned sensor band creates erratic feel that mimics a pressure fault. If the sensors check out, measure steering pressure and trace the full circuit in section 30300S10En_27, starting at page 88.
Manual Section: Adjusting the steering sensorsBoom won't raise to full height, bucket curl stalls or dumps sluggishly under working load p. 114
Confirm the hydraulic oil level (tank capacity approximately 90 l) and that the filter sits within the 1,200-hour service interval on page 10. Inspect cylinder seals for internal leakage; replacement is indicated when damaged or during overhaul (page 67). Compare boost pressure against the 30-32 bar minimum (page 42), then trace the loader control valve circuit starting at page 114.
Manual Section: 30300S10En_36Frequently Asked Questions
What are the torque specs for wheel loader axle/drive components on a GEHL 721?
The manual lists torque specs across the axle and gearbox. Rear axle fasteners run from 8 Nm up to 400 Nm, paired with Loctite 270, 510, 405, 638, and 542. The 20 kph gearbox uses values such as 60 Nm with Loctite 510, 638, and 270. The 40 kph gearbox option lists figures like 80 Nm, 10 Nm, and 190 Nm, again with Loctite 638 and 270.
What are the replacement specifications for hydraulic filters?
On both the 621/721 (model 303-00/304-00) and 721 Telescopic (model 303-10), the hydraulic oil filter insert gets changed at the 'C' and 'D' inspections: every 600 service hours for 'C', and every 1200 service hours or yearly for 'D'.
What are the replacement specifications for fuel filters?
The fuel filter (prefilter and main filter) follows the 'B', 'C', and 'D' inspections on both the 621/721 (model 303-00/304-00) and 721 Telescopic (model 303-10): every 300 service hours for 'B', every 600 for 'C', and every 1200 service hours or yearly for 'D'.
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 Gehl 721, 721T 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.
Document Quality
This document is a high-quality, native digital PDF, allowing you to search and copy the full text content. All text throughout the manual is crisp and clear, ensuring easy readability. Diagrams and illustrations are a mix of sharp vector graphics and clear photos, with all labels consistently readable at various zoom levels. The pages are clean with no noticeable scan artifacts, stains, marks, or skewed content, and there are a few blank "Notes" pages as intended.
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