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OPERATOR'S MANUAL
HAMMER DRILL - 1/2 in. (13 mm)
D550H
VARIABLE SPEED – DOUBLE INSULATED
Your new hammer drill has been engineered and manufactured to Ryobi's high standard for dependability, ease of
operation, and operator safety. Properly cared for, it will give you years of rugged, trouble-free performance.
WARNING: To reduce the risk of injury, the user must read and understand the operator’s manual.
Thank you again for buying a Ryobi hammer drill.
SAVE THIS MANUAL FOR FUTURE REFERENCE
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TABLE OF CONTENTS
■ Introduction ........................................................................................................................................................ 2
■ General Safety Rules .....................................................................................................................................3-4
■ Specific Safety Rules ......................................................................................................................................... 4
■ Symbols ............................................................................................................................................................. 5
■ Specifications .................................................................................................................................................... 6
■ Unpacking .......................................................................................................................................................... 6
■ Applications ....................................................................................................................................................... 6
■ Features .........................................................................................................................................................7-8
■ Operation ......................................................................................................................................................9-13
■ Maintenance ...............................................................................................................................................13-14
■ Parts, Ordering, and Service ........................................................................................................................... 16
INTRODUCTION
Your hammer drill has many features for making the use
of this tool more pleasant and enjoyable. Safety,
performance, and dependability have been given top
priority in the design of this hammer drill making it easy
to maintain and operate.
WARNING:
Do not attempt to use this tool until you have read
thoroughly and understand completely the operator’s
manual. Pay close attention to the safety rules, including Dangers, Warnings, and Cautions. If you
use your tool properly and only for what it is intended, you will enjoy years of safe, reliable service.
WEAR
YOUR
SAFETY
FORESIGHT IS BETTER
GLASSES
THAN NO SIGHT
Look for this symbol to point out important safety
precautions. It means attention!!! Your safety is involved.
The operation of any power tool can result in foreign objects being thrown into your eyes,
which can result in severe eye damage. Before beginning tool operation, always wear safety
goggles or safety glasses with side shields and a full face shield when needed. We
recommend Wide Vision Safety Mask for use over eyeglasses or standard safety glasses
with side shields. Always wear eye protection which is marked to comply with ANSI Z87.1.
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GENERAL SAFETY RULES
WARNING:
Read and understand all instructions. Failure to follow all instructions listed below, may result in electric
shock, fire and/or serious personal injury.
SAVE THESE INSTRUCTIONS
WORK AREA
■ Keep your work area clean and well lit. Cluttered
benches and dark areas invite accidents.
■ Do not operate power tools in explosive atmospheres, such as in the presence of flammable
liquids, gases, or dust. Power tools may create
sparks which may ignite the dust or fumes.
■ Keep bystanders, children, and visitors away
while operating a power tool. Distractions can
cause you to lose control.
ELECTRICAL SAFETY
■ Double insulated tools are equipped with a polarized plug (one blade is wider than the other).
This plug will fit in a polarized outlet only one
way. If the plug does not fit fully in the outlet,
reverse the plug. If it still does not fit, contact a
qualified electrician to install a polarized outlet.
Do not change the plug in any way. Double insu-
lation eliminates the need for the three-wire
grounded power cord and grounded power supply
system.
■ Avoid body contact with grounded surfaces,
such as pipes, radiators, ranges, and refrigerators. There is an increased risk of electric shock if
your body is grounded.
■ Don’t expose power tools to rain or wet conditions. Water entering a power tool will increase the
risk of electric shock.
■ Do not abuse the cord. Never use the cord to
carry the tools or pull the plug from an outlet.
Keep cord away from heat, oil, sharp edges, or
moving parts. Replace damaged cords immediately. Damaged cords increase the risk of electric
shock.
■ When operating a power tool outside, use an
outdoor extension cord marked “W-A” or “W”.
These cords are rated for outdoor use and reduce
the risk of electric shock.
PERSONAL SAFETY
■ Stay alert, watch what you are doing and use
common sense when operating a power tool. Do
not use tool while tired or under the influence of
drugs, alcohol, or medication. A moment of inat-
tention while operating power tools may result in
serious personal injury.
■ Dress properly. Do not wear loose clothing or
jewelry. Contain long hair. Keep your hair, clothing, and gloves away from moving parts. Loose
clothes, jewelry, or long hair can be caught in moving parts or drawn into air vents.
■ Avoid accidental starting. Be sure switch is off
before plugging in. Carrying tools with your finger
on the switch or plugging in tools that have the switch
on, invites accidents.
■ Remove adjusting keys or wrenches before turning the tool on. A wrench or a key that is left at-
tached to a rotating part of the tool may result in
personal injury.
■ Do not overreach. Keep proper footing and balance at all times. Proper footing and balance en-
ables better control of the tool in unexpected situations. Do not use on a ladder or unstable support.
■ Use safety equipment. Always wear eye protection. Dust mask, nonskid safety shoes, hard hat, or
hearing protection must be used for appropriate conditions.
TOOL USE AND CARE
■ Use clamps or other practical way to secure and
support the workpiece to a stable platform. Hold-
ing the work by hand or against your body is unstable and may lead to loss of control.
■ Do not force tool. Use the correct tool for your
application. The correct tool will do the job better
and safer at the rate for which it is designed.
■ Do not use tool if switch does not turn it on or
off. Any tool that cannot be controlled with the switch
is dangerous and must be repaired.
■ Disconnect the plug from power source before
making any adjustments, changing accessories,
or storing the tool. Such preventive safety mea-
sures reduce the risk of starting the tool accidentally.
■ Store idle tools out of the reach of children and
other untrained persons. Tools are dangerous in
the hands of untrained users.
■ Maintain tools with care. Keep cutting tools sharp
and clean. Properly maintained tools with sharp
cutting edges are less likely to bind and are easier
to control.
■ Check for misalignment or binding of moving
parts, breakage of parts, and any other condition that may affect the tool’s operation. If damaged, have the tool serviced before using. Many
accidents are caused by poorly maintained tools.
■ Use only accessories that are recommended by
the manufacturer for your model. Accessories that
may be suitable for one tool, may become hazardous when used on another tool.
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GENERAL SAFETY RULES
SERVICE
■ Tool service must be performed only by quali-
fied repair personnel. Service or maintenance per-
formed by unqualified personnel could result in a risk
of injury.
■ When servicing a tool, use only identical replacement parts. Follow instructions in the Maintenance section of this manual. Use of unauthorized
parts or failure to follow Maintenance Instructions
may create a risk of electric shock or injury.
SPECIFIC SAFETY RULES
Hold tool by insulated gripping surfaces when performing an operation where the cutting tool may contact
hidden wiring or its cord. Contact with a “live” wire will make exposed metal parts of the tool “live” and shock the operator.
ADDITIONAL SAFETY RULES
■ Know your power tool. Read operator’s manual
carefully. Learn its applications and limitations,
as well as the specific potential hazards related
to this tool. Following this rule will reduce the risk
of electric shock, fire, or serious injury.
■ Always wear safety glasses. Everyday eyeglasses have only impact-resistant lenses; they
are NOT safety glasses. Following this rule will re-
duce the risk of serious personal injury.
■ Protect your lungs. Wear a face or dust mask if
the operation is dusty. Following this rule will re-
duce the risk of serious personal injury.
■ Protect your hearing. Wear hearing protection
during extended periods of operation. Following
this rule will reduce the risk of serious personal injury.
■ Inspect tool cords periodically and, if damaged,
have repaired at your nearest authorized service
center. Constantly stay aware of cord location.
Following this rule will reduce the risk of electric
shock or fire.
■ Check damaged parts. Before further use of the
tool, a guard or other part that is damaged should
be carefully checked to determine that it will
operate properly and perform its intended function. Check for alignment of moving parts, binding of moving parts, breakage of parts, mounting, and any other conditions that may affect its
operation. A guard or other part that is damaged
should be properly repaired or replaced by an
authorized service center. Following this rule will
reduce the risk of shock, fire, or serious injury.
■ Do not abuse cord. Never carry the tool by the
cord or yank it to disconnect it from the receptacle. Keep cord away from heat, oil, and sharp
edges. Following this rule will reduce the risk of elec-
tric shock or fire.
■ Make sure your extension cord is in good condition. When using an extension cord, be sure to
use one heavy enough to carry the current your
product will draw. A wire gage size (A.W.G.) of at
least 16 is recommended for an extension cord
100 feet or less in length. A cord exceeding 100
feet is not recommended. If in doubt, use the next
heavier gage. The smaller the gage number, the
heavier the cord. An undersized cord will cause a
drop in line voltage resulting in loss of power and
overheating.
■ Inspect for and remove all nails from lumber before using this tool. Following this rule will reduce
the risk of serious personal injury.
■ Drugs, alcohol, medication. Do not operate tool
while under the influence of drugs, alcohol, or
any medication. Following this rule will reduce the
risk of electric shock, fire, or serious personal injury.
■ Save these instructions. Refer to them frequently
and use them to instruct others who may use
this tool. If you loan someone this tool, loan them
these instructions also.
WARNING:
Some dust created by power sanding, sawing,
grinding, drilling, and other construction activities
contains chemicals known to cause cancer, birth
defects or other reproductive harm. Some examples
of these chemicals are:
• lead from lead-based paints,
• crystalline silica from bricks and cement
and other masonry products, and
• arsenic and chromium from chemically treated lumber.
Your risk from these exposures varies, depending
on how often you do this type of work. To reduce
your exposure to these chemicals: work in a well
ventilated area, and work with approved safety
equipment, such as those dust masks that are
specially designed to filter out microscopic particles.
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SYMBOLS
Important: Some of the following symbols may be used on your tool. Please study them and learn their meaning.
Proper interpretation of these symbols will allow you to operate the tool better and safer.
SYMBOL NAME DESIGNATION/EXPLANATION
V Volts Voltage
A Amperes Current
Hz Hertz Frequency (cycles per second)
W Watt Power
min Minutes Time
Alternating Current Type or a characteristic of current
n
0
.../min Revolutions or Reciprocation Per Minute Revolutions, strokes, surface speed,
The purpose of safety symbols is to attract your attention to possible dangers. The safety symbols, and the
explanations with them, deserve your careful attention and understanding. The safety warnings do not by
themselves eliminate any danger. The instructions or warnings they give are not substitutes for proper accident
prevention measures.
No Load Speed Rotational speed, at no load
Class II Construction Designates double-insulated
construction tools
orbits etc. per minute
Safety Alert Indicates danger, warning or caution.
It means attention!!! Your safety is
involved.
Wet Conditions Alert Do not expose to rain or use in damp
locations.
SYMBOL MEANING
DANGER: Failure to obey a safety warning will result in serious injury to yourself or to others. Always
follow the safety precautions to reduce the risk of fire, electric shock and personal injury.
WARNING: Failure to obey a safety warning can result in serious injury to yourself or to others.
Always follow the safety precautions to reduce the risk of fire, electric shock and personal injury.
CAUTION: Failure to obey a safety warning may result in property damage or personal injury to
yourself or to others. Always follow the safety precautions to reduce the risk of fire, electric shock and
personal injury.
NOTE: Advises you of information or instructions vital to the operation or maintenance of the equipment.
SAVE THESE INSTRUCTIONS
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SPECIFICATIONS
Chuck Capacity 5/64 in. (2 mm) - 1/2 in. (12.7 mm)
Hammer Speed Low (0-16,000 BPM*) & High (0 - 48,000 BPM*)
No Load Speed Low (0 - 1,000/min) & High (0 - 3,000/min)
Input 120 Volts, 60 Hz, AC only, 5.5 Amps
Net Weight 5.75 lbs. (2.6 kg)
* BPM = Blows Per Minute
UNPACKING
INSTRUCTIONS
Your hammer drill has been shipped completely
assembled.
■ Carefully remove the tool from the box. Make sure
that all items listed in the packing list are included.
■ Inspect the tool carefully to make sure no breakage
or damage occurred during shipping.
■ Do not discard the packing material until you have
carefully inspected and satisfactorily operated the
tool.
■ If any parts are damaged or missing, please call
1-800-525-2579 for assistance.
PACKING LIST
Hammer Drill
Carrying Case
Operator’s Manual
WARNING:
If any parts are missing do not operate your tool until
the missing parts are replaced. Failure to do so
could result in possible serious personal injury.
APPLICATIONS
You may use your hammer drill for the purposes listed below:
■ Hammer drilling in concrete, brick, or other masonry.
■ Drilling in wood.
■ Drilling in ceramics, plastics, fiberglass, and laminates.
■ Drilling in both soft and hard metals.
■ Using driving accessories, such as driving screws with screwdriver bits.
■ Mixing paint.
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FEATURES
DOUBLE INSULATION
Double insulation is a concept in safety in electric power
tools, which eliminates the need for the usual three-wire
grounded power cord. All exposed metal parts are
isolated from the internal metal motor components with
protecting insulation. Double insulated tools do not need
to be grounded.
WARNING:
The double insulated system is intended to protect
the user from shock resulting from a break in the
tool's internal wiring. Observe all normal safety precautions to avoid electrical shock.
Important: Servicing of a tool with double insulation
requires extreme care and knowledge of the system and
should be performed only by a qualified service
technician. For service, we suggest you return the tool to
your nearest authorized service center for repair. Always
use original factory replacement parts when servicing.
ELECTRIC MOTOR
Your hammer drill has a precision built electric motor. It
should be connected to a power supply that is 120
volts, 60 Hz, AC only (normal household current). Do
not operate this tool on direct current (DC). A substantial
voltage drop will cause a loss of power and the motor will
overheat. If your tool does not operate when plugged
into an outlet, double-check the power supply.
SWITCH
Your hammer drill has a conveniently located trigger
switch.
VARIABLE SPEED
This tool has a variable speed switch that delivers higher
speed with increased trigger pressure. Speed is controlled
by the amount of switch trigger depression.
REVERSIBLE
This hammer drill allows you to reverse the drill rotation.
You can control the direction of the chuck with a lever
located above the switch trigger.
DRILL MODE
You can change the drill mode depending on the type of
material in which you are drilling.
DEPTH GAUGE ROD
A depth gauge rod is installed on the hammer drill to
assist you in controlling the depth of drilled holes.
CHUCK KEY
A chuck key is provided for use when installing or
removing bits. It is also used when removing the chuck.
AUXILIARY HANDLE
An auxiliary handle is installed on the hammer drill. For
ease of operation, you may use the handle with either the
left hand or the right hand.
ERGONOMIC DESIGN
The design of the hammer drill provides for easy handling.
It is designed for comfort and ease of grasp when
operating in different positions and at different angles.
LOCK-ON
The hammer drill contains a lock-on feature that allows
you to lock the drill on when you operate it continuously
for extended periods of time.
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FEATURES
CHUCK
DEPTH
GAUGE ROD
HANDLE
ASSEMBLY
MODE
SELECTOR
LOCK-ON
BUTTON
SWITCH
TRIGGER
Fig. 1
WARNING:
Do not attempt to modify this tool or create accessories not recommended for use with this tool. Any such
alteration or modification is misuse and could result in a hazardous condition leading to possible serious
personal injury.
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OPERATION
WARNING:
Always wear safety goggles or safety glasses with
side shields when operating this tool. Failure to do
so could result in dust, shavings, or loose particles
being thrown into your eyes, resulting in possible
serious injury.
INSERTING BITS
See Figure 2.
Follow these directions to insert bits.
■ Unplug the hammer drill.
WARNING:
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
■ Position the chuck jaws so that the opening is slightly
larger than the drill bit you intend to use.
NOTE: To open the chuck jaws, turn the chuck collar
counterclockwise. To close the chuck jaws, turn the
chuck collar clockwise.
■ Raise the front of the drill to keep the drill bit from
falling out of the chuck jaws.
CHUCK JAWS
DRILL BIT
CHUCK COLLAR
RIGHT
Fig. 2
WARNING:
Do not insert a drill bit into the chuck jaws and
tighten as shown in Figure 3. This could cause the
drill bit to be thrown from the drill resulting possible
serious injury or damage to the chuck.
■ Insert the drill bit completely into the chuck.
■ Tighten the chuck jaws securely on the drill bit using
the chuck key provided. Do not use a wrench to
tighten or loosen the chuck jaws.
REMOVING BITS
Follow these directions to remove bits.
■ Unplug the hammer drill.
WARNING:
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
■ Loosen the chuck jaws using the chuck key provided.
■ Remove the drill bit from the chuck jaws.
WRONG
Fig. 3
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OPERATION
ADJUSTING THE HANDLE ASSEMBLY
See Figure 4.
Follow these directions to adjust the handle assembly.
■ Unplug the hammer drill.
WARNING:
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
■ Loosen the handle assembly by turning the handle
counterclockwise.
■ Remove the handle from the drill.
■ Rotate the handle assembly and place it on the
opposite side.
■ Tighten the handle assembly securely by turning
the handle clockwise.
ADJUSTING THE DEPTH GAUGE ROD
See Figure 5.
Follow these directions to adjust the depth gauge rod.
■ Unplug the hammer drill.
HANDLE
ASSEMBLY
HANDLE
ADJUST DEPTH
GAUGE ROD
Fig. 4
WARNING:
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
■ Loosen the handle assembly by turning the handle
counterclockwise.
■ Adjust the depth gauge rod so that the drill bit extends beyond the end of the rod to the required
drilling depth.
■ Tighten the handle assembly by turning the handle
clockwise.
ADJUSTING THE DRILL MODE
See Figure 6.
Adjust the drill mode when necessary. We recommend
that you use carbide-tipped bits and select hammer
mode when drilling in hard materials such as brick, tile,
concrete, etc. We recommend that you select drill mode
when drilling in soft materials.
Follow these directions to adjust the drill mode.
■ Unplug the hammer drill.
WARNING:
HANDLE
SLIDE RIGHT FOR
DRILLING MODE
TO
LOOSEN
TO
TIGHTEN
Fig. 5
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
■
For hammer mode
left.
■
For drill mode
: Slide the mode selector to the
: Slide the mode selector to the right.
10
SLIDE LEFT FOR
HAMMER MODE
Fig. 6
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OPERATION
ADJUSTING THE SPEED
See Figure 7.
The hammer drill has a two-speed knob that provides a
high speed of approximately 3,000 RPM and a low
speed of approximately 1,000 RPM (stated speeds are
with the trigger switch in the “Full-on” position).
Follow these directions to adjust the speed.
■ Unplug the hammer drill.
COUNTERCLOCKWISE
TO LOW SPEED
WARNING:
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
For high speed
■
wise, aligning the indicator mark with the “2.”
■
For low speed
clockwise, aligning the indicator mark with the “1.”
If you have difficulty changing from one gear range to the
other, turn the chuck by hand until the gears engage.
: Rotate the two-speed knob clock-
: Rotate the two-speed knob counter-
CAUTION:
Never change gears while the tool is running. Failure
to obey this caution could result in serious damage
to the drill.
CHANGING THE ROTATION
See Figure 8.
The direction of the chuck is controlled by the lever
located above the switch trigger.
Follow these directions to change the rotation.
■ Unplug the hammer drill.
1
CLOCKWISE TO
HIGH SPEED
2
Fig. 7
FORWARD
ROTATION
REVERSE
ROTATION
WARNING:
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
■
For forward rotation
■
For reverse rotation
NOTE: The hammer drill will not run unless the lever
is pushed fully to the left or right.
: Move the lever to the left.
: Move the lever to the right.
CAUTION:
The hammer drill is not designed for reverse hammering. Failure to obey this caution may result in
property damage.
Fig. 8
DEPRESS SWITCH TRIGGER TO
TURN HAMMER DRILL ON
Fig. 9
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-
OPERATION
TURNING THE HAMMER DRILL ON/OFF
See Figure 9.
Follow these directions to turn the hammer drill on and
off.
■
To turn the drill on
To turn the drill off
■
LOCKING ON
See Figure 10.
The lock-on feature allows you to lock the drill on when
you operate it continuously for extended periods of time.
If you have the “lock-on” feature engaged during use and
the drill is disconnected from the power supply, disengage
the “lock-on” feature immediately. Also, do not lock the
trigger switch if you might need to suddenly stop the drill.
WARNING:
: Depress the switch trigger.
: Release the switch trigger.
LOCK-ON
BUTTON
SWITCH
TRIGGER
Fig. 10
Before connecting the hammer drill to a power supply, make sure it is not in the “locked-on” position.
Failure to do so could result in accidental starting of
the drill resulting in possible serious injury.
Follow these directions to lock on.
■ Depress the switch trigger.
■ Push in the lock-on button.
■ Release the switch trigger.
■ Release the lock-on button.
NOTE: To release the lock, depress the switch trigger.
DRILLING
See Figure 11.
Follow these directions to drill.
■ Depress and release the switch trigger to make sure
the drill is in the OFF position before connecting it to
a power supply.
■ Check the rotation lever for the correct setting. Refer to “CHANGING THE ROTATION” earlier in this
manual.
■ Secure the material to be drilled in a vise or with
clamps to keep it from turning as the drill bit rotates.
■ Plug the hammer drill into a power supply.
■ Hold the drill firmly and place the bit at the point to
be drilled.
■ Depress the switch trigger to start the drill.
■ Move the drill bit into the workpiece applying only
enough pressure to keep the bit cutting.
-
2
1
1
Fig. 11
WARNING:
Be prepared for binding or breakthrough. When these
situations occur, the drill has a tendency to grab and
kick in the opposite direction and could cause loss of
control when breaking through material. If you are
not prepared, this loss of control could result in possible serious injury.
NOTE: Do not force the drill or apply side pressure
to elongate a hole. Let your drill and bit do the work.
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OPERATION
HELPFUL TIPS
■ When drilling hard, smooth surfaces, use a center
punch to mark the desired hole location. This measure will prevent the drill bit from slipping off center
as you start the hole. However, the variable speed
feature allows you to start holes without center
punching. To accomplish this, operate the drill at a
low speed until you start the hole.
■ When drilling metals, use a light oil on the drill to
keep it from overheating. The oil will prolong the life
of the bit and increase the drilling action.
■ If the bit jams in the workpiece or if the drill stalls,
stop the tool immediately. Remove the bit from the
workpiece and determine the reason for jamming.
MAINTENANCE
WARNING:
When servicing use only identical Ryobi replacement parts. Use of any other parts may create a hazard or cause
product damage.
GENERAL
Avoid using solvents when cleaning plastic parts. Most
plastics are susceptible to damage from various types of
commercial solvents and may be damaged by their use.
Use clean cloths to remove dirt, carbon dust, etc.
WARNING:
Do not at any time let brake fluids, gasoline, petroleum-based products, penetrating oils, etc. come in
contact with plastic parts. They contain chemicals
that can damage, weaken, or destroy plastic.
When electric tools are used on fiberglass boats, sports
cars, wallboard, spackling compounds, or plaster, it has
been found that they are subject to accelerated wear and
possible premature failure, as the fiberglass chips and
grindings are highly abrasive to bearings, brushes,
commutators, etc. Consequently, we do not
recommended that this tool be used for extended work
on any fiberglass material, wallboard, spackling
compounds, or plaster. If, however, you do work with any
of these materials, it is extremely important that the tool
is cleaned frequently by blowing with an air jet.
LUBRICATION
All the bearings in this tool are lubricated with a sufficient
amount of high grade lubricant for the life of the unit
under normal operating conditions. Therefore, no further
lubrication is required.
WARNING:
Always wear safety goggles or safety glasses with
side shields during power tool operation or when
blowing dust. If operation is dusty, also wear a dust
mask.
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MAINTENANCE
REMOVING THE CHUCK
See Figures 12, 13, and 14.
Follow these directions to remove the chuck.
■ Unplug the hammer drill.
MALLET
WARNING:
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
■ Open the chuck jaws by turning the chuck collar
counterclockwise.
■ Insert a 5/16 in. (7.9 mm) or larger hex key into the
chuck.
■ Tighten the chuck jaws using the chuck key provided.
■ Loosen the chuck screw by tapping the hex key
sharply with a mallet in a clockwise direction.
■ Open the chuck jaws and remove the hex key.
■ Remove the chuck screw by turning it in a clockwise
direction with a screwdriver.
NOTE: The screw has left hand threads.
■ Reinsert the hex key into the chuck.
■ Tighten the chuck jaws securely using the chuck key
provided.
■ Loosen the chuck by tapping the hex key sharply
with a mallet in a counterclockwise direction.
■ Unscrew the chuck by hand.
CHUCK
JAWS
CHUCK
HEX KEY
Fig. 12
SCREWDRIVER
Fig. 13
TIGHTENING THE CHUCK
See Figures 12 and 13.
The chuck may become loose on the spindle and begin
to shake when using the drill. Also, the chuck screw may
become loose causing the chuck jaws to bind and
prevent them from closing.
Follow these directions to tighten the chuck.
■ Unplug the hammer drill.
WARNING:
Failure to unplug the tool could result in accidental
starting causing possible serious injury.
■ Open the chuck jaws by turning the chuck collar
counterclockwise.
■ Insert a 5/16 in. (7.9 mm) or larger hex key into the
chuck.
■ Tighten the chuck jaws using the chuck key provided.
■ Tap the hex key sharply with a mallet in a clockwise
direction to tighten the chuck on the spindle.
MALLET
HEX KEY
CHUCK JAWS
■ Open the chuck jaws and remove the hex key.
■ Tighten the chuck screw by turning it in a counter-
clockwise direction with a screwdriver.
NOTE: The screw has left hand threads.
CHUCK
Fig. 14
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NOTES
15
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OPERATOR'S MANUAL
HAMMER DRILL - 1/2 in. (13 mm)
D550H
VARIABLE SPEED – DOUBLE INSULATED
EXTENSION CORD CAUTION
When using a power tool at a considerable distance from a
power source, be sure to use an extension cord that has the
capacity to handle the current the tool will draw. An undersized cord will cause a drop in line voltage, resulting in overheating and loss of power. Use the chart to determine the minimum wire size required in an extension cord. Only round jacketed cords should be used.
When working with a tool outdoors, use an extension cord
that is designed for outside use. This is indicated by the letters
"WA" on the cord's jacket.
Before using any extension cord, inspect it for loose or exposed wires and cut or worn insulation.
**Ampere rating
(on tool faceplate) 0-2.0 2.1-3.4 3.5-5.0 5.1-7.0 7.1-12.0 12.1-16.0
Cord Length Wire Size (A.W.G.)
25' 16 16 16 16 14 14
50' 16 16 16 14 14 12
100' 16 16 14 12 10 —
CAUTION: Keep the extension cord clear of the working
area. Position the cord so that it will not get caught on
lumber, tools or other obstructions while you are working
with a power tool.
**Used on 12 gauge - 20 amp circuit.
• SERVICE
Now that you have purchased your tool, should a need ever exist for repair parts or
service, simply contact your nearest Ryobi Authorized Service Center. Tool service
must be performed only by qualified repair personnel. Be sure to provide all pertinent
facts when you call or visit. Please call 1-800-525-2579 for your nearest Ryobi
Authorized Service Center. You can also check our Web site at www.ryobitools.com
for a complete list of Authorized Service Centers.
• MODEL NO. AND SERIAL NO.
The model number of this tool will be found on a plate attached to the motor housing.
Please record the model number and serial number in the space provided below.
• HOW TO ORDER REPAIR PARTS
983000-129
9-02
WHEN ORDERING REPAIR PARTS,
ALWAYS GIVE THE FOLLOWING INFORMATION:
• MODEL NUMBER
D550H
• SERIAL NUMBER
RYOBI TECHNOLOGIES INC.
1428 Pearman Dairy Road Anderson, SC 29625
Post Office Box 1207 Anderson, SC 29622
www.ryobitools.com
Phone 1-800-525-2579
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