Cub Cadet SC 621 Operator'S Manual Download Page 14

14

General Recommendations

Always observe safety rules when performing any 
maintenance.

The warranty on this lawn mower does not cover 
items that have been subjected to operator abuse 
or negligence. To receive full value from the 
warranty, operator must maintain the lawn mower 
as instructed in this manual. 

Changing of engine governed speed will void 
engine warranty. 

Some adjustments will have to be made 
periodically to maintain your unit properly. All 
adjustments in the Making Adjustments section of 
this manual should be checked at least once each 
season. 

Periodically check all fasteners and make sure 
these are tight.

Follow the maintenance schedule under Customer 
Responsibilities to get quality performance from 
your lawn mower.

Lubrication

WARNING: Always stop engine and
disconnect spark plug wire before
cleaning, lubricating or doing any kind of
service work on the lawn mower.

Blade Control: Lubricate the pivot points on the blade 
control handle at least once a season with light oil. The 
blade control must operate freely in both directions. 
See Figure 16.

Wheels: Lubricate the wheels at least once a season 
with light oil (or motor oil). If the wheels are removed for 
any reason, lubricate the surface of the axle bolt and 
inner surface of the wheel with light oil. See Figure 16.

Engine: Follow the separate engine manual packed 
with you unit for lubrication instructions.

Figure 16

Maintenance

NOTE: When tipping the unit, empty the fuel tank and
keep the spark plug side of engine up. Never tip the
mower more than 90 degrees and do not leave the
mower tipped for any length of time. Oil can drain into
the upper part of the engine causing a starting problem.

Engine

Refer to the separate engine manual for all engine 
maintenance instructions.

Maintain engine oil as instructed in the separate 
engine manual packed with your unit.

Service air cleaner every 25 hours under normal 
conditions. Poor engine performance and flooding 
usually indicate that the air cleaner should be 
serviced. To service the air cleaner, refer to the 
separate engine manual packed with your unit.

The spark plug should be cleaned and the gap 
reset once a season. Spark plug replacement is 
recommended at the start of each mowing season.

Clean the engine regularly with a cloth or brush. 
Keep the cooling system (blower housing area) 
clean to permit proper air circulation which is 
essential to engine performance and life. Be certain 
to remove all grass, dirt, and combustible debris 
from muffler area.

Deck

The underside of the mower deck should be cleaned 
after each use to prevent a buildup of grass clippings, 
leaves, dirt, or other matter. If this debris is allowed to 
accumulate, it will invite rust and corrosion, and may 
prevent proper mulching, discharge, or bagging.  The 
deck may be cleaned by tilting the mower and scraping 
clean with a suitable tool (make certain the spark plug 
wire is disconnected).

IMPORTANT:

 We do not recommend the use of a 

pressure washer or garden hose to clean your unit.

Cutting Blade Removal, Replacement, and Sharpening

When removing the cutting blade for sharpening or 
replacement, protect your hands with a pair of 
heavy gloves or use a heavy rag to hold the blade.

Remove the bolt and the blade bell support which 
hold the blade and the blade adapter to the engine 
crankshaft. See Figure 17.

Remove the blade and the adapter from the 
crankshaft.

WARNING: Periodically inspect the blade
adapter for cracks, especially if you strike
a foreign object. Replace when necessary.

Lubricate

Summary of Contents for SC 621

Page 1: ...the engine s exhaust system is equipped with a spark arrester meeting applicable local or state laws if any If a spark arrester is used it should be maintained in effective working order by the operator In the State of California the above is required by law Section 4442 of the California Public Resources Code Other states may have similar laws Federal laws apply on federal lands A spark arrester ...

Page 2: ...eed help from our Customer Support Department or an authorized dealer You can locate the model number by looking down at the rear of the deck A sample model plate is explained below For future reference please copy the model number and the serial number of the equipment in the space below CALLING CUSTOMER SUPPORT If you have difficulty assembling this product or have any questions regarding the co...

Page 3: ...en overlooked and could be accidentally thrown by the mower in any direction and cause serious personal injury to the operator or any others allowed in the area Wear sturdy rough soled work shoes and close fitting slacks and shirts Shirts and pants that cover the arms and legs and steel toed shoes are recommended Do not wear loose fitting clothes or jewelry They can be caught in moving parts Never...

Page 4: ...e slope gauge Do not mow on wet grass Reduced footing could cause slipping CHILDREN Tragic accidents can occur if the operator is not alert to the presence of children Children are often attracted to the mower and the mowing activity Never assume that children will remain where you last saw them Keep children out of the mowing area and under the watchful care of a responsible adult other than the ...

Page 5: ...low objects to be thrown For safety protection frequently check components and replace with manufacturer s recommended parts when necessary Mower blades are sharp and can cut Wrap the blade s or wear gloves and use extra caution when servicing them Do not change the engine governor setting or overspeed the engine Excessive engine speeds are dangerous WARNING YOUR RESPONSIBILITY Restrict the use of...

Page 6: ... N T I N G A 1 5 S L O P E WARNING Do not mow on inclines with a slope in excess of 15 degrees a rise of approximately 2 1 2 feet every 10 feet A riding mower could overturn and cause serious injury If operating a walk behind mower on such a slope it is extremely difficult to maintain your footing and you could slip resulting in serious injury Operate RIDING mowers up and down slopes never across ...

Page 7: ...seated securely into the handle mounting brackets Tighten the wing nuts on each side of the handle carriage bolts must be seated properly into the handle See Figure 2 NOTE Your mower is shipped with the handle in the higher height position If you wish to lower the height of the handle refer to the Adjustment Section at this time Remove the hairpin clips from the outer hole in the weld pins on the ...

Page 8: ...er The blade control handle must be depressed in order to operate the unit Release blade control handle to stop engine and blade See Figure 6 WARNING This blade control mechanism is a safety device Never attempt to bypass its operations Rear Cutting Height Adjustment Lever The rear wheel cutting height adjustment lever is located above the left rear wheel The front wheel cutting height is determin...

Page 9: ...llowing questions With the drive clutch control released push mower forward and pull it backward Does it move freely Towards Better Mower Performance 1 Read this manual in its entirety before you start the lawn mower Instructions given here have been designed for maintaining safety while getting the best performance from your mower Follow the instructions closely 2 Pour fresh clean gasoline into t...

Page 10: ...rottle which is set at full throttle for best performance Stand behind the mower and squeeze the blade control handle against the upper handle Grasp recoil starter handle and pull rope out slowly until engine reaches the start of compression cycle rope will pull slightly harder at this point Let the rope rewind slowly Pull rope with a rapid continuous full arm stroke Keeping a firm grip on the sta...

Page 11: ...o move the starter rope out of the way of the bag when the chute door is opened Figure 9 Emptying the Grass Bag While holding the grass bag by both the rear handle and the lower handle lift the grass bag straight up off the adapter The chute door will move the rope out of the way of the bag Continue to hold the lower handle and raise the rear of the grass bag up toward your chest The grass bag wil...

Page 12: ...dle Height Adjustment Your mower is shipped with the handle in the higher height position To lower the height proceed as follows Remove the starter rope from the rope guide Remove the upper handle by removing the hand knobs and carriage bolts Lay the upper handle out of the way being careful not to bend or kink the cables Remove the hairpin clips from the weld pins on the handle brackets Press out...

Page 13: ...n the adjustable cable bracket and tighten hex nut Figure 15 Engine Adjustments See the separate engine manual packed with your unit for adjustments to the engine SECTION 7 MAINTAINING YOUR LAWN MOWER Adjustment Bottom View Wheel Drive Clutch Control Upper Handle Bottom View Speed Control Lever Upper Handle Hex Nut Adjustable Cable PUSH Bracket Customer Responsibilities MAINTENANCE SCHEDULE PRODUC...

Page 14: ...ausing a starting problem Engine Refer to the separate engine manual for all engine maintenance instructions Maintain engine oil as instructed in the separate engine manual packed with your unit Service air cleaner every 25 hours under normal conditions Poor engine performance and flooding usually indicate that the air cleaner should be serviced To service the air cleaner refer to the separate eng...

Page 15: ... your mower the blade bolt must be checked periodically for correct torque Drive Belt Removal and Replacement Disconnect the spark plug wire and ground it against the engine Drain the fuel tank or place a piece of plastic beneath the cap to prevent gasoline leakage Place shift lever in the first position and tip the mower on its side Remove the center bolt which secures the blade to the crankshaft...

Page 16: ...so that the belt is not in the pulley groove and the lower pulley can be pushed towards the engine See Figure 22 Pivot the control arm back to its original position and reinstall the six speed cable into the slot See Figure 23 Check and make sure the belt is routed inside the pulley halves and the belt guard pin Figure 23 Reinstall the bolt securing transmission to rear mower housing Transmission ...

Page 17: ...ected 3 Fuel tank empty or stale fuel 4 Blocked fuel line 5 Faulty spark plug 1 Engage blade control handle 2 Connect wire to spark plug 3 Fill tank with clean fresh gasoline 4 Clean fuel line 5 Clean adjust gap or replace Engine runs erratic 1 Spark plug wire loose 2 Blocked fuel line or stale fuel 3 Vent in gas plugged 4 Dirty air cleaner 5 Carburetor out of adjustment 1 Connect and tighten spar...

Page 18: ...ference only 41 40 65 36 24 17 21 19 34 18 13 28 26 32 29 11 20 26 28 35 12 14 15 30 33 26 31 25 16 27 23 22 64 38 7 66 2 2 37 39 60 51 58 55 59 61 56 16 25 31 4 5 73 4 5 74 87 85 86 84 83 82 9 9 8 10 8 68 68 67 69 70 48 49 48 81 78 79 76 54 53 46 47 50 44 45 52 77 80 43 80 77 75 6 1 3 6 2 88 ...

Page 19: ...39 24 23 732 0803A Spring Lever 67 742 0741 21 Mulching Blade 24 732 0832 Torsion Spring 68 748 0377C Blade Adapter 25 736 0270 Bell Washer 285 x 75 x 082 69 736 0524A Blade Bell Support 26 736 0369 Flat Washer 508 I D 1 000 x 020 70 710 1257 Hex Bolt 3 8 24x2 5 Lg 27 738 0529 Shoulder Nut 825 Dia x 165 Lg 73 731 1832 Side Discharge Chute 28 741 0324 Hex Flange Bearing 506 I D x 590 L 74 731 1833 ...

Page 20: ...20 Model SC 621E 16 21 18 20 23 22 17 19 24 A 26 25 A 28 27 29 14 30 2 2 4 36 3 5 1 5 3 7 6 34 33 31 32 35 39 40 56 12 11 42 41 46 38 50 54 47 44 45 51 37 53 49 52 55 ...

Page 21: ...16 731 0904A Upper Control Housing 41 725 0873 Ignition Switch 17 731 0924 6 Speed Shift Lever 42 725 0201 Ignition Key 18 713 0397 Gear Insert 44 725 1206 Plug 19 710 1667 C Sunk Tap Screw 10 16x 625 45 625 0021 Wire Harness 20 732 0627 Shift Lever Spring 46 710 1270 Hex Bolt 1 4 20 x 1 3 Lg 21 16864 6 Speed Rack Cable Brkt 47 736 0270 Bell Washer 1 4 I D 22 731 0905A Lower Control Housing 49 782...

Page 22: ...22 Model SC 621 16 21 18 20 23 22 17 19 24 A 26 25 A 28 27 29 11 13 14 15 30 2 2 4 36 3 5 1 5 3 34 33 31 32 35 37 6 8 ...

Page 23: ...37 736 0451 Saddle Washer Ref No Part No Part Description Model SC 621 Ref No Part No Part Description 1 710 1174 Carriage Bolt 5 16 18 x 2 0 2 714 0104 Cotter Pin 072 x 1 12 Lg 3 720 0241 Knob Ass y Wing Nut 5 16 18 4 726 0240 Strap 4 3 Lg 5 736 0451 Saddle Washer 320 ID x 830 OD 6 712 0429 Hex Nut 5 16 8 710 1270 Oval C Sunk Screw 11 712 0324 Lock Nut 1 4 20 13 746 0883 Control Housing 14 746 09...

Page 24: ...x 75 x 062 9 736 0329 Lock Washer 1 4 Reg Duty 10 736 0526 Wave Washer 1 38 x 88 x 029 11 738 0924 Shoulder Screw 375 x 1 4 14 12 750 1070 Sleeve Spacer 88 ID x 1 00 OD 13 750 1071 Sleeve Spacer 88 ID x 1 13 ID 14 756 0625 Roller Cable 15 782 7574 6 Speed Cable Adj Bracket 16 782 7575 6 Speed Cable Mt Bracket 17 782 7596 6 Speed Control Arm 18 782 7597 6 Speed Pivot Bracket 19 712 0138 Hex Nut 1 4...

Page 25: ...0 Flat Washer 885 x 1 45 14 721 0329 Oil Seal 15 618 0253 Upper Housing Assembly 16 736 0616 Thrust Washer 504 x 70 17 717 1487 Pinion Shaft 10T 18 736 0314 Thrust Washer 3 8 x 70 19 736 0569 Thrust Washer 388 x 625 20 618 0252 Lower Housing Assembly 21 710 0642 Hex Screw 1 2 20 x 75 22 782 7601A Cable Bracket 23 741 0674 Bearing 24 611 0066 Shaft Assembly 25 721 0325 Plug 26 717 1469 Gear 34T 27 ...

Page 26: ...26 NOTES ...

Page 27: ...27 ...

Page 28: ...adet equipment used commercially is warranted for one year only Commercial use is defined as either having hired operators or used for income producing purposes Items not covered The warranty does not cover routine maintenance items such as lubricants filters oil fuel air and hydraulic cleaning tune ups brake and or clutch inspection adjustments made as part of normal maintenance blade sharpening ...

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