Part of the John Deere Repair Manuals.
Arguments about whether a 640D power train is worn out or simply out of adjustment end at a test port, and TM1441, the 438-page John Deere 640D technical manual PDF covering both the 640D and 648D skidders, is where those tests live. Wiring diagrams trace the starting, charging, parking brake and secondary steering circuits back to the battery. The hydraulic section takes the main pump, stroke control valve, surge relief valve and steering crossover relief valve from theory through diagnosis to a pressure test, and the winch closes things out the same way. Pressurize the cooling system to 69 kPa (0.7 bar) (10 psi) when you are chasing a leak, and retire a transmission pump that will not make 42 L/min (11.0 gpm) new. Most breakdowns happen with nobody around for you to ask. Bookmarked and text searchable, it points at the failed part before you phone in the order.
What's Inside This John Deere 640D Skidder & 648D Grapple Skidder Manual
| System | Pages | Key Topics |
|---|---|---|
| General Information | 7-38 | Safety Information, General Specifications, Torque Values, Fuels and Lubricants |
| Operational Checkout Procedure | 39-62 | Gauges, Indicators, Hourmeter, Park Brake Indicator, Control Lever, Linkages, Neutral Start Switch, Speed Control |
| Engine Operation and Tests | 63-110 | Theory of Operation, Diagnostic Information, Adjustments, Tests |
| Electrical Operation and Tests | 111-170 | Batteries, Starting Circuit, Starting Motor, Charging Circuit, Alternator, Parking Brake, Secondary Steering Circuit, Gauges |
| Power Train Operation and Tests | 171-294 | Theory of Operation, Diagnostic Information, Adjustments, Tests |
| Hydraulic System Operation and Tests | 295-401 | Main Hydraulic Pump, Stroke Control Valve, Hydraulic Charge Pump, Surge Relief Valve, Hydraulic Manifold, System Relief Valve, Steering Valve, Steering Crossover Relief Valve |
| Miscellaneous Components (Winch) Operation and Test | 402-438 | Theory of Operation, Diagnostic Information, Adjustments, Tests |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Blade lift cylinders (2) rod diameter | 1.75 in. (44.5 mm) | p. 20 |
| Blade lift cylinders (2) bore | 4.00 in. (101.6 mm) | p. 20 |
| Cooling System Test Pressure | 69 kPa (0.7 bar) (10 psi) | p. 102 |
| Transmission Pump Minimum Flow (New Pump) | 42 L/min (11.0 gpm) | p. 242 |
| Transmission Pump Minimum Flow (Used Pump) | 41 L/min (10.0 gpm) | p. 242 |
| Rod length adjustment | 6.4 mm (0.25 in.) | p. 235 |
| Slow idle adjustment | 800 ± 50 rpm | p. 89 |
| Intake Valve Lift | 11.68-12.45 mm (0.460-0.490 in.) | p. 97 |
| Crankshaft End Play (Not To Exceed) | 0.38 mm (0.015 in.) | p. 98 |
| Engine Oil Pressure (Slow Idle) | 100 kPa (1.0 bar) (15 psi) minimum | p. 101 |
| Fuel Transfer Pump Pressure (Minimum) | 15-30 kPa (0.15-0.3 bar) (2-4 psi) | p. 103 |
John Deere 640D Skidder & 648D Grapple Skidder Common Problems This Manual Covers
John Deere 648D transmission slipping under load, slow engagement and low clutch charge pressure
Check transmission oil level and condition before you chase anything else. Test charging pump output against the 42 L/min (11.0 gpm) new pump minimum listed on page 242; a used pump holding under 41 L/min (10.0 gpm) is worn out. Replace the pump, then recheck engagement before heading back to the landing.
Manual Section: Powershift Transmission Malfunctions p. 242Machine moves in only some gears, or forward works but reverse is inconsistent
Start at the disconnect clutch linkage before anyone talks about pulling the transmission. Adjust rod length to the 6.4 mm (0.25 in.) figure given on page 235, then run a clutch pressure test in each gear. If lube pressure falls below the 240 kPa (35 psi) minimum on page 247, suspect internal leakage.
Manual Section: Disconnect Clutch Malfunctions p. 235Boom and blade functions slow and weak, hydraulics chattering and running hot
Warm the oil to operating temperature, then load the main pump to the 13790 kPa (138 bar) (2000 psi) test pressure on page 363 and read flow. Watch charge pressure at the same time: anything under 35 kPa (0.35 bar) (5 psi) means the pump is starving. Clean the suction screen and check for a collapsed inlet hose.
Manual Section: Hydraulic System Malfunctions p. 363Engine runs hot on long skids and loses coolant with no puddle underneath
Pressure test the system cold at 69 kPa (0.7 bar) (10 psi) per the value on page 102 and hold it fifteen minutes. If it bleeds down with nothing dripping, pull the cap and look for combustion bubbles. Blow the core out from the fan side; forestry chaff packs it solid.
Manual Section: Engine Malfunctions p. 102Grapple tongs close slowly and drift open while holding a hitch of stems
Check the tong cylinder for bypass by bottoming the rod, holding pressure, and watching for creep. Match your parts against the 5.50 in. (139.7 mm) bore on page 22 and the 19.74 in. (501.5 mm) stroke on page 22 before ordering a seal kit, then retest under a full hitch.
Manual Section: General Information p. 22Frequently Asked Questions
What is the diagnostic procedure for John Deere 648D no-start issues?
To diagnose a no-start condition, first perform the Operational Checkout Procedure in Section 9005-10. If the engine still will not start, check for an empty fuel tank, a plugged fuel tank vent, or water in the fuel system. Ensure there is electrical power to the injection pump solenoid by listening for a click when the key is turned to the ON position. p. 74
What is the minimum transmission pump flow on a John Deere 640D or 648D?
The transmission pump flow test calls for at least 42 L/min (11.0 gpm) from a new pump; a used pump below 41 L/min (10.0 gpm) is worn. p. 242
What is the specified valve clearance for the John Deere 640D Skidder & 648D Grapple Skidder engine?
The intake valve clearance is 0.36 mm (0.014 in.) and the exhaust valve clearance is 0.46 mm (0.018 in.). p. 94
What is the correct fan belt deflection specification for a John Deere 640D Skidder & 648D Grapple Skidder?
The fan belt deflection should be 19 mm (0.75 in.) when measured midway between the pulleys with a force of 111 N (25 lb force) applied. p. 93
What is the engine oil pressure spec at slow idle on a John Deere 640D Skidder & 648D Grapple Skidder?
The engine oil pressure at slow idle must be a minimum of 100 kPa (1.0 bar) (15 psi). p. 101
Is this John Deere 640D manual a download or a disc?
A 438-page Technical Manual in searchable PDF format, available the moment you complete checkout. View on computer, tablet, or phone, with no shipping wait.
Am I able to print pages from this John Deere 640D manual?
Print away. There is no DRM and no page limit. Many buyers print one chapter at a time and leave the rest on a tablet.
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