Within the hour you could have this Allis Chalmers 720 repair manual PDF open on the bench beside a dead hydrostat, all 129 pages of factory document TP 500-0504-01-PM-SA covering the 616, 620, and 720 tractors. Wiring diagrams trace each circuit from the battery through the charging, ignition, starting, and PTO switch checks, and hydraulic schematics map the power lift valve and cylinder. The in-line hydrostatic section takes the pump, motor, and center section apart and back together, closing with a priming procedure, an exploded view, and a test after repair. Check charge pump pressure at three quarter to full throttle against the 50 to 150 psi spec, then confirm the implement relief reads 550 to 800 psi. A guessed clearance costs you a second teardown. Bookmarked and text searchable, this PDF goes wherever the tractor quit, shed or field, so hay does not wait on a parts counter.
What's Inside This Allis Chalmers 616, 620, 720 Repair Manual
| System | Pages | Key Topics |
|---|---|---|
| General Information | 1-17 | Battery Care (Battery Removal and Installation, Water Level, Charging, Winter Care) |
| Engine | 18-20 | Tractor Hood, Battery, Fuel Lines, Oil Cooler, Engine Shrouds, PTO Coupling, Clutch Pedal, Spark Plugs |
| Wheels and Drop Housings | 21-26 | Removal and Installation of Wheel, Removal and Disassembly of Drop Housing, Inspection and Repairs of Drop Housing, Assembly and Installation of Drop Housing, Brakes (Description, Operation, Removal and Disassembly of Brake Assembly, Brake Levers and Linkage, Inspection and Repair) |
| Power Train System | 27-33 | Brake Assembly, Hydrostatic Transmission, Three-Speed Gear Transmission, Differential Gear Assembly, Clutch and Drive Shaft, Rear PTO |
| Transmission | 34-40 | Transmission Case, Hydrostatic Pump, Shift Shaft Assembly, Shift Forks, Differential Case, PTO Shaft, Brake Assemblies |
| Differential | 41-42 | Differential Assembly, Gear Carrier, Pinion Shafts, Bearing Cones, Bearing Cups, Thrust Washers, Spring Washers |
| Rear PTO | 43-46 | Rear PTO Drive Unit, Differential Assembly, Transmission Case, Oil Cooler, Electric Clutch, Steering Wheel, Instrument Panel Assembly |
| Final Drive | 47-52 | Rear PTO Drive Unit, Drive Shaft Assembly, Intermediate Gear Assembly, Final Gear Assembly, Transmission Case, Hydrostatic Pump |
| Steering and Front Axle Assemblies | 53-69 | Steering Shaft Assembly, Steering Gear Assembly, Front Axle Assembly, Hub Assembly, Spindle Assembly, Drag Link, Tie Rod |
| Power Lift System | 70-75 | Description, Function, Hydraulic Control Valve Removal and Installation, Hydraulic Cylinder Removal, Hydraulic Cylinder Installation, Oil Cooler Removal, Inspection |
| Electrical System | 76-99 | Description, Wiring Harness, Battery Circuit, Battery Condition, Battery Wiring |
| Fuel System | 100-105 | Description, System Operation, Fuel Tank and Fuel Gauge (Removal, Inspection and Installation), Air Cleaner (Removal, Cleaning and Installation) |
| In-Line Hydrostatic Unit | 106-129 | Specifications, Hydraulic Fluid Recommendations, System Description, Pump/Motor, Charge Pump and Check Valves, Control, Implement Relief Valve, Acceleration Valves |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Charge pump pressure | 50-150 psi | p. 14 |
| Implement reading | 550-800 psi | p. 14 |
| Rectifier-Regulator | 13.4-14.7 vdc at 1800-3600 rpm | p. 99 |
| Battery | 45 ampere sealed terminals | p. 99 |
| Transmission Fluid Change Interval | 400 hours | p. 13 |
| Clutch Pedal Free Travel | 1 to 2 inches | p. 15 |
| Clutch Belt Tension Spring Length | 7-3/4 inches | p. 15 |
| Hydrostatic Pump Input Speed (Max) | 4000 RPM | p. 106 |
| Implement Relief Setting | 550-800 PSI | p. 106 |
| Engine Horsepower | 19.5 H.P. | p. 99 |
Allis Chalmers 616, 620, 720 Common Problems This Manual Covers
Allis Chalmers 620 three-point hitch won't lift, hydro drives fine but lift cycles erratically
Check the hydraulic fluid level before pulling anything apart. Tee a gauge in and run the engine at three quarter throttle; charge pressure should read 50 to 150 psi per the page 14 test, with implement relief holding 550 to 800 psi. Good pressure with a dead lift means removing the control valve for inspection, page 70.
Manual Section: Power Lift System p. 70Battery goes dead overnight and ammeter shows no charge at any engine speed
Test battery voltage at the posts with the engine running 1800 to 3600 rpm; the rectifier-regulator should hold 13.4 to 14.7 vdc per the specs on page 99. No rise means the 20 ampere alternator or stator connections are suspect. Trace the harness against the wiring diagram on page 76 and clean every ground before condemning the stator.
Manual Section: Electrical System p. 99Starter won't crank, or engine turns over but won't fire after sitting all winter
Check the neutral start switch, PTO switch, and ignition switch with a test light; these old toggle switches corrode open and kill the crank circuit. Work the checkout procedure on page 98, then measure the PTO clutch coil for 2.88 ohms per page 99. Replace any switch that reads open instead of jumpering around it.
Manual Section: Engine Troubleshooting p. 98Hydrostatic drive jerks under load and loses power on hills when the fluid warms up
Drain and change the transmission fluid and filter if you're past the 400 hour interval on page 13; a plugged 25 micron filter starves the charge pump. Then gauge charge pressure, which should hold 70 to 150 PSI per page 110. Low pressure with fresh fluid points to worn check valves in the hydrostatic unit, page 106.
Manual Section: In-Line Hydrostatic Unit p. 106Drive belt squeals and tractor creeps forward with the clutch pedal fully depressed
Measure clutch pedal free travel by hand; you want 1 to 2 inches per page 15. Adjust the linkage to spec, then check the clutch belt tension spring at its engaged length of 7-3/4 inches. A stretched spring or glazed belt slips under load, so fix it now and finish the mowing before the weather turns.
Manual Section: Clutch Pedal Free Travel Adjustment p. 15Frequently Asked Questions
What are the torque specs for SAE Grade 5 hardware on the Allis Chalmers 616, 620, 720 tractors?
The torque specifications for plated SAE Grade 5 hardware vary by size. For example, a 1/4-20 bolt requires 8 foot-pounds, a 3/8-16 bolt requires 30 foot-pounds, and a 1/2-13 bolt requires 75 foot-pounds. Refer to the table in Figure 2 for a complete list of specifications for various bolt sizes. p. 12
What is the recommended transmission fluid and filter change interval for the Allis Chalmers 616, 620, 720?
The transmission fluid and filter should be changed every 400 hours of operation. The filter must also be changed whenever the transmission case is drained and refilled. p. 13
What is the correct clutch pedal free travel distance?
The clutch pedal free travel should be between 1 and 2 inches. If the distance is outside this range, you must adjust the locknut on the clutch linkage. p. 15
What is the required torque for the engine mounting bolts on an Allis Chalmers 616, 620, 720 tractor?
When installing the engine, the mounting bolts must be torqued to 20 foot-pounds to ensure proper alignment with the PTO drive shaft. p. 20
What is the correct spark plug gap for the Allis Chalmers 616, 620, 720 Tractor engine?
The spark plug gap must be set to 0.025 of an inch. New plugs should be installed every 100 hours of operation. p. 20
Will this Allis Chalmers 616 Repair Manual download right away?
A single searchable PDF file of 129 pages, downloadable right after payment. Nothing ships, nothing waits in the mail.
Is this Allis Chalmers 616 Repair Manual printable?
Absolutely. No DRM or copy protection. Print the whole manual or just the pages you need. Any home or office printer works.
Reviews
There are no reviews yet.