Publication 9803/3150 gives you the full 242-page factory service manual for the JCB 805, 805B, 806B, 807B, and 808 mini excavators. Hydraulic circuit schematics map the neutral, slew, track, and excavator operating modes for each variant, and the electrical diagrams carry component keys, warning lights, cable colour codes, and switch layouts across the range. Dedicated sections walk through the hands-on work: pump dismantling, relief valve bench testing, ram rebuilds, track and slew gearbox overhaul, rotary coupling service, and starter motor teardown. Slew ring bolts torque to 405 Nm (300 lbf ft), the hydraulic filter element renews every 400 hours, and the engine oil filter every 200. When your machine is parked and the dealer quotes a week, the answer is here: bookmarked by section, searchable by keyword. Load it on a tablet and get wrenching.
What's Inside This JCB 805 & variants Manual
| System | Pages | Key Topics |
|---|---|---|
| General | 16-23 | Lubricants and Capacities, Service Schedule, Grease Points (All Pivot Pins, Each Slewing Ring Nipple and Rotary Coupling, Slewing Ring Teeth) |
| Pumps and Motors (Commercial) | 24-39 | Hydraulic Filter (Early Type), Technical Data (Continued), Technical Data, Relief Valve Operating Pressures, River Maintenance Rig, Rams, Filtration, Filter Operation |
| JCB 805B From M/C No. 200607 | 40-61 | Motor Spool (Husco) with Brake Vent Valve, Circuit Operation, Standard Spool Operation, Example, Method of Operation, Non-Return Valves, Typical Spool-Track, Excavator & Attachment Service Valves |
| Offloading Valve (in Valve Block-Pilot Operated) | 62-77 | Auxiliary Relief Valves (Rubery Owen and Husco), Relief Valves - Excavator & Attachment Service Valves, Excavator Relief Valve Operation, Auxiliary Relief Valve Operation, Operation, Valve Closed, Pilot Valve Opens, Dump Valve Opens |
| Pressure Testing | 78-93 | Offloading Valve Operation (Commercial), Operation, Off Loading Valve (Commercial), Dismantling and Assembly, When Assembling, Main Relief Valves-Track Block (JCB 805, 806B |
| Track & Slew Valve (Hamworthy) | 94-109 | Hydraulic Circuit - Excavator Operating, Track/Slew Valve Block - Slew Operating, Track/Slew Valve Block - Neutral Circuit, Hydraulic Circuit - Neutral, Hydraulic Circuit - Slew Operating, Track/Slew Valve Block - One Track Operating, Hydraulic Circuit - Tracks Operating, Track/Slew Valve Block - Two Tracks Operating |
| Variable Boom Drop Restrictor (From M/C No. 77307) | 110-125 | Pressure Testing (Hamworthy), Excavator Valve (Hamworthy), Track & Slew Valve (Hamworthy), Slew Relief Valve (a), When Dismantling, When Assembling, Offloading Valve (B), Non-Return Valves (C |
| Circuit Diagram JCB 805B (to M/C No. 200147) | 126-141 | Rotary Coupling, Beam Clamp Control Valve (to M/C No. 200297), Beam Clamp Cylinder, Beam Clamp Operation, Dismantling and Assembly, When Dismantling, When Assembling, Port Connections |
| Fault Finding (Continued) | 142-149 | Circuit Diagram JCB 805B (From M/C No. 200148 to 200205), Neutral Circuit (Bold Line), Boom, Dipper and Bucket Services, Off-Loading Valve, Track Service, Slew Service, Beam Clamp |
| Attachments | 150-155 | Attachment Service Valve, Hose Connections, Grab Gearbox (Rotating Head) |
| Body & Framework | 156-167 | Cab (Glazing), Hydraulic Tilt Cab (System Bleeding), Slew Ring (When Replacing), Slew Ring Seal (Replacement) |
| Gearboxes | 168-188 | Track Gearbox, Slew Gearbox, Slew Gearbox Oil Level 805B, Track Gearbox (Primary Reduction), Track Gearbox (Secondary Reduction) |
| Track & Running Gear | 189-200 | Tracks (Inspect, Clean, Check, Adjust), Track (Removal and Replacement, When Removing, When Replacing), Rollers (Dismantling and Assembly) |
| Engine | 201-216 | Technical Data, Engine Oil Perkins, Engine Oil 2700 Series, Engine Oil Filter, Engine Fuel Filters, Engine Fuel Sediment Bowl, Engine Fuel Lift Pump, Engine Fuel System Perkins |
| Electrics | 217-236 | Technical Data, Circuit Diagram, Circuit Diagram 805, 806B, 807B, 808 (Main Components, Warning Lights, Lights, Cable Colour Code, Switches) |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Hydraulic Fault Reset Procedure | Not specified; manual provides fault finding checks and actions, not a general reset procedure. | p. 145 |
| Slew Ring Bolts Torque | 405 Nm (300 lbf ft) | p. 163 |
| Engine Oil Filter Replacement Interval | Every 200 Hours | p. 204 |
| Hydraulic Filter (Early Type) Replacement Interval | Every 400 Hours | p. 31 |
| Hydraulic Filter (Later Type) Replacement Interval | Every 400 Hours | p. 32 |
| Engine Fuel Filter Replacement Interval | Every 400 Hours | p. 205 |
| Engine Fuel Sediment Bowl Drain Interval | Every 50 Hours | p. 206 |
| Fan Belt Check Tension Interval | 50 Hours | p. 212 |
| Fan Belt Deflection | approximately 10mm (0.4in.) | p. 212 |
| Track Tension | 25mm (1in.) | p. 189 |
| Battery Voltage | 12 volt | p. 217 |
| Battery Capacity | 128 Amp hour | p. 217 |
JCB 805 & variants Common Problems This Manual Covers
JCB 805 series engine cranks but won't start after storage or maintenance, no fuel delivery p. 206
Drain the sediment bowl every 50 hours (page 206) and replace fuel filter elements every 400 hours (page 205). After any fuel system work, bleed air from the lines following the Engine Fuel System Bleeding procedure. Verify the fuel shutoff solenoid connector is seated and the lift pump delivers flow before suspecting injection pump components.
Manual Section: Engine Fuel System BleedingHydraulic boom and stick response sluggish under load, bucket loses digging force p. 145
Check hydraulic oil level and top up if low. Replace filter elements at 400 hours (page 31). Test track main relief valve pressure with a calibrated gauge; spec is 193 bar (page 25). If pressure reads correct but functions stay slow, work through the fault finding chart on page 145 to pinpoint a sticking spool, blocked restrictor, or worn pump.
Manual Section: Hydraulics Fault FindingTracks sagging loose and riding high on sprocket, derailing during tight turns p. 189
Measure track sag at the midpoint between front idler and rear sprocket; correct tension is 25mm (1in.) deflection (page 189). Add grease through the adjuster nipple in small increments until the measurement is correct. Recheck tension after the first hour of work following any adjustment, as new track beds in and sag increases.
Manual Section: Track & Running GearEngine temperature climbs under load, gauge approaches red zone during extended digging p. 212
Inspect the fan belt for wear and measure deflection; correct spec is approximately 10mm (0.4in.) at midspan, checked every 50 hours (page 212). When tightening, follow bolt sequence C, B, A. Clean the radiator matrix of mud and debris. Replace the air cleaner outer element every 100 hours (page 18) to maintain adequate airflow through the cooling system.
Manual Section: EngineOil pressure warning light remains on after engine starts and idles normally p. 204
Verify engine oil level on the dipstick and top up if low. Replace the oil filter element every 200 hours (page 204), as a clogged element starves oil pressure at startup. If oil level and filter condition are correct, test the warning lamp sender circuit through the Electrics section starting at page 217 before condemning the oil pump.
Manual Section: ElectricsFrequently Asked Questions
What are the replacement specifications for engine oil filter?
The engine oil filter element should be renewed every 200 hours. For normally-aspirated engines, unscrew bolt A, remove the filter body and element B, discard the element, clean all metal parts, and reassemble with a new element and seal C. For turbocharged engines, unscrew element D, discard the element, clean the filter head, and reassemble with a new element.
What are the replacement specifications for hydraulic filters?
Renew the hydraulic filter element every 400 hours. On early type filters, remove the filler cap, plug B, and U-bolt C, unscrew bolt D, withdraw element E, wash the metal parts in JCB 'Special' Hydraulic Fluid, then reassemble with a new element and seal F. On later type filters, take off the tank filler cap and filter plug A, drain at plug C, remove access plate B (if fitted), unscrew bolt D and element E, wash the metal parts in JCB 'Special' Hydraulic Fluid, and reassemble with a new element and seal F.
What format is this manual in?
Immediate download of the complete 242-page searchable Service Manual. Access it on any device: laptop at your desk or phone in the field.
Can I print specific sections of this Service Manual?
The PDF is DRM-free, so print whatever sections you need for the shop. Standard letter or A4 paper works.
Are electrical wiring diagrams included in this JCB 805 & variants manual?
Yes, this JCB 805 & variants Service Manual includes complete electrical wiring diagrams, wire routing, and connector pinouts.
Document Quality
This is a scanned document, not a native digital PDF. An OCR layer is present, allowing you to search and copy text, though the quality of the underlying scanned text varies, with some areas appearing faded or blurry. Diagrams and illustrations are raster images; while many are clear enough, some exhibit fading or scan artifacts, and labels can be faint. Page condition is inconsistent, with many pages showing visible scan artifacts, stains, marks, and skewed content, particularly on the revision history pages. Several blank pages are included throughout the document.
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