Howard Gem Rotavator Workshop Service Repair Manual

Service and Repair Manual

Service Manual INTRODUCTION This service manual has been compiled to give HOWARD Dealers and their staff, a sequence of operations to enable the servicing and repair of a HOWARD GEM ROTAVATOR to be carried out quickly and effectively. Because of our policy of continuous improvement, this manual should always be used in conjunction with the latest service bulletins covering the GEM. These service bulletins are distributed to all HOWARD horticultural dealers when they are first printed, and back issues are available from us on request. HOWARD GElVl service bulletins after bulletin H.63, should be kept with this manual, and a note added to the index of each section affected, so that an up to date record of modifications is kept. At the start of each section, there is a list of ordinary workshop tools that will be required when carrying out the repairs covered by that section. Some 'special tools' may also be required, of which a complete list can be found under 'special tools' section 'A'. In addition to the special tools and equipment used during some repairs, a hydraulic or hand operated fly press (of the type found in most workshops) will be required when removing and fitting oilseals and bearings. Before assembly of component parts, remove dirt and grease and, in the case of new parts, remove the special rust inhibitor, otherwise the function of the component may be restricted when in operation. When ordering spare parts, DO NOT confuse the illustration numbers used in this manual with the TRUE part numbers found in the official parts list, form number L.693. While every effort is made to ensure that the information contained within this manual is correct, any errors which may occur, should be brought to the attention of our Service Department. SECTION Specifications, torque loadings, special tools. A Engine removal, clutch, clutch shaft, air cleaner. B Gearbox, wheels and hubs. C Controls. D Main frame, handlebars, shields. E Rotor, rotor clutch, drive chain, backplate. F Lubrication, maintenance and fault finding. G PAGE 3 7 19 37 4 5 5 1 6 1 Although this manual refers to machines in current production, reference is made, where possible, to the history of the various assemblies and components. ILLUSTRATION REFERENCE The figures in brackets after component names refer to the illustration number of the component, within thediagram specified by that instruction. e.g. (C25-35) is Section 'C' illustration '25' illustrated component 35-Reverse idler gear.

Howard Gem HISTORY OF THE GEM The HOWARD GEM has been developed over a period of many years. Since its introduction in 1942, there have been five series of GEM, each series being an improved version of its predecessor. SERIES I The original GEM was fitted with 'bicycle type' handlebars, but was not equiped with either a differential or a reverse gear. Series 1 machines were produced from serial number 101 up t o machine serial number 4800, and these machines were fitted with the HOWARD B.J. engine. SERIES ll 'Swinging type' handlebars and a differential were introduced at the start of the series II GEM, and later they were equiped with a reverse gear operated by a lift up lever. Series II machines were produced from serial number 4801 up to machine serial number 14784, and these machines were fitted with the original HOWARD B.J. or a J.A.P. 600cc engine. SERIES Ill AND IV Production of series I II and IV machines overlapped. The basic machine remained the same for both, only the engines were different. Series I l l machines were produced from serial number 14785, and were fitted with either the HOWARD B.J. or a J.A.P. 600cc engine. During production of the series I II, the first series IV machines were phased in. These machines were fitted with a new HOWARD engine, the 180° Twin. From machine serial number 38760 series l V machines only were produced, but were fitted with an improved version of the twin engine-the HOWARD 360° Twin -or alternatively a water cooled Sachs diesel engine. Series IV machines were discontinued at machine serial number 47066. SERIES V This is the current series of GEM, which was introduced at machine serial number 47067. Machines up to serial number 2541824 were fitted with an up-rated version of the HOWARD 360° Twin engine, or the Sachs diesel. From machine serial number 2541825, a Kohler K.301T engine has been fitted in place of the twin, or from machine serial number 2571945, an alternative diesel engine, the Hatz ES.780, has been used. An improved version of the Hatz engine has been fitted from machine serial number 250A1021, and is designated the Hatz ES780U. SUPER GEM The super GEM is an up-rated version of the Series V model produced specifically for contract work where greater strength and power are required. Super GEM machines are fitted with either a Kohler K341 petrol or Hatz E785 diesel engine.

Section A - Srpecifications SPEC1FICATIONS STANDARD GEM Kohler K301T 4 stroke petrol, producing 11h.p. (rnax.) at 2800 r.p.m. governed engine speed 22 Ib-ft (30Nm) torque at 2200 r.p.m. SLIPER GEM Kohler K341T 4 stroke petrol, producing 15h.p. (rnax.) at 2800 r.p.rn. governed engine speed 28 Ib-ft (38Nrn) torque at 2100 r.p.rn. STANDARD GEM Hatz ES780U stroke diesel producing 9h.p. (max.) at 3000 r.p.m. governed engine speed 19 Ib-ft (25.75 Nm) torque at 2100 r.p.m. SUPER GEM Hatz E785 4 stroke diesel producing 1 'I h.p. (rnax.) at 3000 r.p.m. governed engine speed 23 Ib-ft (31Nm) torque at 2100 r.p.rn. These engines are air cooled and fitted with an automatic compression release for easy starting. TRANSiVllSSlON 3-forward gears and one reverse. Full differential with an automatic locking device on engaging the rotor. Rotor safety clutch with a slip action when under shock load. ENGINE CLUTCH Single plate, heavy duty, dry friction plate. CONTROLS All situated within easy reach of the operator, and are as follows: 1. Clutch lever. 2. Throttle lever. 3. Gear lever with spring out safety device when using reverse gear. 4. Handlebars adjustable for height and side swing. 5. Rotor selector and differential lock control. 6. Depth setting lever. ROTOR Rotor speed 188 rpm at an engine speed of 2800 rprn. Rotor widths of 20" (51 em), 24" (61 cm) and 30" (76 cm). Tillage depth is adjustable down to 9" (23 crn). WHEELS 20" overall diameter using 4.00 x 12 2-ply pneumatic tyres. Tyre pressure is 20 1blin2(1.4 kg/cm2). LANDSPEEDS At 2800 rprn. engine speed:-- 1st gear - 0.96 mph. - 1.4 kph 2nd gear - 1.46 mph. - 2.3 kph 3rd gear - 3.05 mph. - 4.9 kph Reverse - 1.85 rnph. - 2.9 kph The above landspeeds refer to machines built after serial number 250A1021 only. These machines are the current production model, fitted with either the Kohler K.301TIK341T or the Hatz ES.780UIE785 engines and the latest 3617 ratio crownwheel and pinion. (See the crownwheel and pinion history in section 'B').

Section A - Specifications WEIGHT Petrol model Diesel model 20" - 644 Ibs (292 kg) 652 Ibs (296 kg) 24" - 672 Ibs (305 kg) 674 Ibs (306 kg) 30" - 790 Ibs (358 kg) SUPER GEM Petrol model Diesel model 24" - 630 Ibs + dead weights 746 Ibs (338 kg) 30" - 862 Ibs (391 kg) RECONlNlENDED LUBRICANTS Gearbox and chaincase - SAE 90 gear oil, all others oiling points use - engine oil. TORQUE LOADINGS All nuts and bolts must be kept tight, and as a guide the following table of torque loadings may help. In the absence of a suitable torque wrench, spanners of the length specified in the right hand column of the table below, will, if used to maximum effect by the average man, give comparable loadings. Thread size t" BSW 5" BSW - i 6 2'' BSW & UNC g' BSW & UNC 1," BSW & UNC 2'' BSW 2" BSF 5" BSF BSF 16 1," BSF 5" BSF 2" BSF Blade bolt and nut Torque loading lbs/f t kg/m Spanner length inches cms 5 12.5 6 15 7 17.5 8 20 10 25 18 45 5 12.5 6 15 8 20 10 25 18 45 36 91.5 12 30 SPECIAL EQUIPMENT HERMATITE - is a sealing compound used, where specified, to prevent the possibility of oil leaks. Manufactured by :- Kenilworth Manufacturing Co. Ltd. Hermatite Works, West Drayton, Middlesex, ENGLAND. SAMPSON C. 110 GLUE - is an Amyl Acetate glue used, where specified, to secure the fibre discs to the rotor clutch drive discs. Manufactured by :- Samuel Jones & Co. Ltd., Sampson Adhesive Mill, St. IVeots, Huntingdonshire, ENGLAND'

- Section A - Special Tools SPECIAL TOOLS The following special tools w,ill be required when carrying out certain repairs, and as they are simple in design, can be easily produced from the following dimensioned drawings. SPECIAL TOOL S.1:- is a clutch shaft puller used, as specified in instruction '3a' Section 'B', to remove a broken clutch shaft. SPECIAL TOOL S.2:- is a hub puller used, as specified in instruction '2' Section 'C', to remove the wheel hubs. SPECIAL TOOL S.3:- is a pegged tool used, as specified in Section 'C'. 'To dismantle the axle assembly: to remove the loose hub gear bearing. SPECIAL TOOL S.4:- is an axle shaft puller used, as specified in Section TF' Rotor stub axle-to remove', to remove the unbroken stub axle. SPECIAL TOOL S.5:- is a pegged tool used, as specified in Section 'F' Rotor drive shaft - to remove', to remove the rotor drive shaft sprocket bearing. SPECIAL TOOL S.6:- is a pegged tool used, as specified in instruction '89' Section 'C' to remove the bearing from the gearbox jackshaft. SPECIAL TOOL S.7:- is a pointer used in conjunction with 2-2 " BSW nuts, as specified in instruction '5b' Section 'B', to enable the crownwheel to pinion backlash t o be assessed.

Section A - Special Tools 72 Drill and tap bar to accept 2 Drill and tap tube ' UN F x 2" long setscrews. t o accep' 5. . .-.r. 3, 8 SPECIAL TOOL S.l 6" dia. I %" UNC x 2" " UNC nut welded long . I L - ,- UIVL x 1" long square headed setscrews SPECIAL TOOL S.3 %" UNC x 3" long setscrew SPECIAL TOOL S.2 I weld then file to shape of stub axle. SPECIAL TOOL S.4 2 pins SPECIAL TOOL S.5 2 Holes Dia. SPECIAL TOOL S.6 \c' SPECIAL TOOL S.7

Section B CONTENTS Subject Action ADJUSTMEIVTS BELL HOUSING Fitting-Hatz -Kohler Removal-Hatz -Kohler CLUTCH SHAFT AND PINION HISTORY CLUTCH SHAFT Fitting Removal CLUTCH SHAFT BEARING Fitting Removal DRIVE ADAPTOR Fitting-Hatz -Kohler Removal-Hatz -Kohler ENGl blE-HATZ Description Fitting Removal KOHLER Description Fitting Removal ENGINE CLUTCH Assemble Dismantle Fitting Removal Page 18 11 10 11 10 8 16 13 15 15 11 10 11 9 8 17 10 8 17 9 13 12 16 11 SERVICE BULLETINS APPERTAINING TO THIS SECTION ARE:- TOOLS LIST No. off No. off 1 Small (electrical) screwdriver 1 Small punch 1 Large screwdriver 1 CopperIRawhide mallet 1 M" BSW Open ended spanner 1 Pair 6" engineers pliers 1 M" BSW Box spanner 1 Pair right angled internal circlip pliers 1 ;" BSW Open ended spanner 1 Pair straight internal circlip pliers 1 ;" BSW Ring spanner 1 '-" BSW Ring spanner 'Z,r AF Ring spanner 1 2"AFBoxspanner 1 g" AF Open ended spanner 1 ;" AF Ring spanner 1 ,'," Sq. Extended box spanner 1 12mm Open ended spanner 1 13mm Open ended spanner Bulletin No. - - - - - - -- SPECIAL EQUIPMENT Date -- - - Hermatite Steel rule Containerltray of at least 6 pints capacity SPECIAL TOOLS Special tool S. 1 Special tool S.7 and 2.;" BSW Nuts

Section B HISTORY ENGINES The Kohler K.301T has been fitted from machine serial number 2541 825 and is a 477cc 4-stroke petrol engine of 10hp. From machine serial number 2571945, the Hatz ES.780 diesel engine has been available as an alternative to the Kohler engine. The Hatz is a 500cc 4-stroke diesel engine of 10 hp. An improved version of the Hatz engine, having an antivibration front cover and designated ES.780U, has been fitted from machine serial number 250A1021. ENGINE CLUTCH All Kohler and Hatz engined machines are now fitted with a single plate clutch. Machines prior to serial number 2571414, were fitted with a double plate clutch, and the following parts are required if converting the clutch assembly to the single plate version. Part number 288 255 250 Part description Thrust sleeve Distance piece Special bolt No. Off 1 4 4 The clutch assembly should be rebuilt substituting these parts for the existing components, and one fibre disc and one loose plate should be discarded from the original assembly. A new clutch shaft - part number 25009 - will also be required. CLUTCH SHAFTICROWIUWHEEL AND PINION The crown wheel and pinion were changed on GEM 24" models - machine serial numbers 2592305 and 2306; GEM 30" models - machine serial numbers 2591063, 1067, 1069, 1070, 1138, 1139, 1189, 1190, 1191, 1394 and 1451, and all GEM V models from machine serial number 250A1021. The ratio of the gears was changed from 3619 to 3617 in order to reduce the forward travel speed of the machine, and thus increase its performance. The later ratio gears can be supplied and fitted to machines prior to machine serial number 250A1021, but as a pair only, as the new and the old bevel gears are not interchangeable and must be used with their respective pinions. New parts Old parts Part number 27367 Bevel gear Part number 25008 Bevel gear Part number 27368 Clutch shaft Part number 25009 Clutch shaft Part number 25007 Pinion Part number 25061 Special nut Part number 208010160 Split pin. NOTE The new 7- tooth pinion is an integral part of clutch shaft - part number 27368 - and this shaft can only be used with the single plate clutch assembly. When fitting the new bevel gear - part number 27367 - to the gearbox jackshaft 6-hr'dia. x "long rivets (part number 208023040) will be required in place of the original ,& "dia. x a " long rivets, which are too short LO secure the new bevel gear.

Section B TO REMOVE THE KOHLER ElUGllVE 1. Refer to illustration "B 1 " unless otherwise stated. la. Disconnect the throttle control (569) from the engine by releasing the small clamp bolt and cable clamp on the side of the engine. Ib. Slacken the jubilee clip on the carburettor induction elbow end of the air cleaner hose (595), and remove the hose from the elbow. Ic. Disconnect the stop switch cable (573) from the engine mounted condenser. Id. Turn off the fuel supply from the petrol tank at the fuel filter bowl, and disconnect the pipe from the tank. Drain off any fuel in the pipe before removing from the engine. le. With the engine suitably supported (on blocks etc.), remove the 8-setscrews (558) from around the perimeter of the clutch bell housing (556). The machine may then be moved clear of the engine. TO FIT THE ENGl NE - See instruction 6. TO REMOVE THE DRIVE ADAPTOR (551)'- KOHLER ENGINE To remove the drive adaptor from the engine crankshaft, remove the square plug (557) from the side of the bell housing (556), and loosen the square headed setscrew (554) using an extended k" square box spanner through the hole in the side of the housing. Slide the adaptor from the housing, and retain the locating key (555) (and spacer if fitted). If the drive adaptor bearing (553) is to be renewed, the old bearing may be pressed out from the back of the adaptor, with the aid of a 1" dia. drift. The new bearing can then be pressed into its location, greased, and secured by positioning the special washer (552) over the bearing (domed side outermost), and with the aid of a small punch, burr the lip of the bearing housing over the washer in 3 or 4 places.

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Howard Gem Rotavator Workshop Service Repair Manual

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