Built from factory content for the Perkins-powered 20-series fleet, this 196-page manual (OEM #50940187) carries the documentation Gehl techs work from. The wiring diagrams trace every harness, from the drive forward-reverse controller out to the joystick and roof harness, and the electrical chapter steps through faults from a starter that won't turn to four-wheel steering that refuses to engage. Hydraulic schematics cover both the hydrostatic drive circuit and the work hydraulics. It also includes 5 pages of calibration procedures and a troubleshooting section sorted by symptom. Wheel nuts torque to 420 ±20 Nm; fill the hydraulic tank to 90 liters and change the oil filter at 1,200 service hours. Every section is bookmarked and keyword-searchable, so you can pull it up on a tablet right at the machine.
What's Inside This Gehl 520, 521, 620 Manual
| System | Pages | Key Topics |
|---|---|---|
| Contents & Overview | 3 | Engine, Fuel Lines, Cooling, Frame, Hydrostatic Drive, Front Axle |
| Technical Specifications | 4-16 | Engine, Hydrostatic Drive, Front Axle, Brakes, Steering, Loader Unit |
| Operator Station & Controls | 17-19 | Front Instrument Panel, Front Controls, Operator's Seat, Side and Rear Controls |
| Implement & Bucket Controls | 20-21 | Implement, Sensor Operating Point, Automatic Bucket Repositioning Mode |
| Engine | 22-32 | Engine Specifications, Valve Tip Clearance, Rocker Assembly, Cylinder Head Assembly, Fuel Pump, Recommended Tightening Torques |
| Fuel System | 33-34 | Fuel Filter, Water Separator, Suction Line, Reflux Line, Fuel Tank, Stop Cock |
| Cooling System | 35-36 | Water Cooler, Oil Cooler, Water Pump, Temperature Sensor, Expansion Tank, Drain Valve |
| Frame & Attachments | 37-38 | Frame, Attachment, Counterweight |
| Hydrostatic Drive System | 39-88 | Reflux From Tank, Radiator, Oil Cooler, Boost Pressure Valve, Hp Valves, Boost Pump |
| Axles & Final Drives | 89-94 | Planet Gear, Roller Bearing, Sun Gear Shaft, Ring Gear, O-Ring Sealing, Hub |
| Brake System | 95-98 | Brake Pedals, Expansion Tank, Master Brake Cylinder, Brake Light Switch, Air Bleed Valve, Pressure Difference Valve |
| Hydrostatic Drive Controls | 99-101 | Solenoid Front & Rear Axle Lock, Drive Pump, Boost Pump, Solenoid High Speed, Measuring Point Boost Pressure, Pressure Line |
| Steering System | 102-106 | Solenoid Front & Rear Axle Diff Lock, Hp Pump, Priority Valve, Rear Axle Steering Ram, Servostat, Steering Valve |
| Electrical System | 107-139 | Solenoid Valve, Pressure-Sensing Switch, Flame Heater Plug, Starter, Cutoff Solenoid, Battery |
| Electrical, Sensors & 4-Wheel Steering | 140-149 | Flat Plug, Earthing Connection, Magnet 1st Speed, Rear Sensor, Front Wheel Steer, Four-Wheel Steering |
| Wiring Harnesses | 150-155 | Wiring Harness (Drive), Wiring Harness (Differential Lock), Wiring Harness (Load Stabilizer), Plug Housing, Plugs |
| Wiring Diagrams | 156-163 | - |
| Cab Electrics & Instruments | 164-165 | Front Wiper Motor, Wiper Arm, Instrument Panel, Steering Column |
| Hydraulic System | 166-184 | - |
| Steering & Brake Hydraulic Circuits | 185-188 | Steering (Servostat), Steering Ram, Priority Valve, Master Brake |
| Cab Heating | 189-196 | - |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| General tightening torques for screws (8.8 strength class) | 3 Nm (M4) to 1420 Nm (M30) | p. 10 |
| Wheel nut tightening torque | 420 ±20 Nm | p. 10 |
| Hydraulic oil filter replacement interval | every 12 months or 1200 service hours | p. 21 |
| Engine Oil Capacity | 11 ltr. | p. 18 |
| Hydraulic Oil Tank Capacity | About 90 ltr. | p. 18 |
| Fuel Tank Capacity | 90.0 ltr. | p. 18 |
| Brake System Brake Fluid Capacity | 0.5 ltr. | p. 18 |
| Wheel Nut Torque | 420 ±20 Nm | p. 10 |
| Max. Service Pressure (Hydrostatic Drive) | 465 bar | p. 7 |
| Max. Axle Load (front and rear) | 4,600 kg | p. 8 |
| 520 | ||
| Engine 520 Output | 53 kW / 72 HP, 2.200 rpm | p. 5 |
| 620 | ||
| Engine 620 Output | 58.5 kW / 79.5 HP, 2.200 rpm | p. 5 |
Gehl 520, 521, 620 Common Problems This Manual Covers
Gehl 520/521/620 hydraulic pump grinding noise after 2000 hours, bucket lifts slowly or won't raise p. 55
Start by checking the hydraulic oil level; tank capacity is about 90 ltr. (page 18). Inspect the hydraulic filter and replace it if it's past the 1,200-hour service interval. Measure boost pressure at the point shown on page 55; a reading below spec points to a worn pump or a clogged suction strainer.
Manual Section: Hydrostatic Drive Troubleshooting (General)Engine won't start or cranks slowly after sitting, starter turns but nothing fires p. 122
Verify the battery charge; spec is 12 V, 100 Ah (page 9). Trace the cutoff solenoid and starter circuit beginning on page 107. If it cranks but won't fire, drain the water separator on page 33 and confirm the fuel shutoff is open. Then test each safety interlock switch: one open contact kills the whole crank circuit.
Manual Section: Engine No-Start / Starting IssuesHydraulic oil temperature warning light comes on during heavy digging, system overheats p. 123
Inspect the water cooler and oil cooler on page 35 for debris packing, and check the coolant level. Confirm the hydraulic oil sits at the 90 ltr. fill mark on page 18. If temperature stays high under load, work through the overheating chart on page 123 and check the cooler fan drive belt for slippage or breakage.
Manual Section: Hydraulic System OverheatingDiesel engine running but machine won't move, no forward or reverse drive p. 122
Confirm the hydrostatic drive oil level, then read boost pressure at the test port on page 55; max service pressure is 465 bar (page 7). Inspect the high-speed solenoid and drive pump connections on page 99. If the machine moves one direction only, go straight to the vehicle movement chart on page 122 and test the directional solenoid coils.
Manual Section: Vehicle Movement IssuesLoader bucket drifts down slowly with controls at neutral, cylinder won't hold position p. 55
Examine the lift and tilt cylinder seals for internal leakage. Trace the holding valve circuit in the hydraulic schematic on page 41, then measure cylinder holding pressure at the diagnostic test port on page 53. If pressure drops under static load, the seals or the control valve spool are bypassing. Tank capacity is 90 ltr., so check the oil level as well.
Manual Section: 303S2200Frequently Asked Questions
What are the torque specs for a GEHL 520/521/620?
Torque values run throughout this section. Cylinder-head bolts call for 110 Nm, connecting rod nuts 125 Nm, and main bearing screws 265 Nm. Hydraulic fittings vary by thread size and seal type; an M10X1.0 fitting with a sealing washer takes 7 (9) lb.-ft. (Nm).
How do I replace or repair the hitch on a GEHL 520?
To rebuild the quickhitch ram, remove the circlip first, then pull out the piston rod together with the guide bushing. Unscrew the self-locking nut, fit the complete sealing kit, and reassemble in reverse order. The manual's hydraulic cylinder section gives the exact tightening torque and the detailed sealing-kit fitting steps.
What are the replacement specifications for Hydraulic filters?
Change the hydraulic oil filter insert at the 1st Inspection (100 service hours), then every 300 service hours. Replace it at least every 12 months or 1200 service hours, or sooner if the instrument-panel telltale calls for it. Maintenance kits for plans B, C, and D include the filter, part number 0 00 363 66 34.
How quickly can I access this Gehl 520, 521, 620 manual after buying?
A 196-page service manual in searchable PDF, ready to download the moment checkout completes. Open it on a computer, tablet, or phone. No shipping wait.
Is this Gehl 520, 521, 620 Service Manual printable?
No restrictions at all. Print individual pages, full chapters, or the entire manual. The PDF is completely unlocked.
Does this Gehl 520, 521, 620 manual include hydraulic schematics?
Yes. The manual includes hydraulic circuit diagrams, system schematics, and component specifications with pressure ratings.
Document Quality
This document is a scanned PDF with an OCR layer, allowing you to search the full text and copy content. The text quality is generally good and readable throughout, with some pages appearing crisper than others. Diagrams and illustrations are primarily raster images, meaning labels might lose some sharpness when zoomed in significantly, though they remain legible. The page condition is clean, with no notable scan artifacts, stains, or skewed pages. There are a few intentionally blank pages, specifically pages 2, 12, and 178.
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