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ELECTRICAL

EXTENSION CORDS

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 listed by Underwriter’s Laboratories 
(UL) should be used.
When working outdoors with a tool, use an extension cord 
that is designed for outside use. This type of cord is desig-
nated with “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 data plate)

 

 

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 

**Used on 12 gauge - 20 amp circuit.

NOTE:

 AWG = American Wire Gauge

WARNING:

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. Failure to do so can result in serious personal 
injury.

WARNING:

Check  extension  cords  before  each  use.  If  damaged
replace immediately. Never use tool with a damaged cord 
since touching the damaged area could cause electrical 
shock resulting in serious injury.

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 insulation. Observe all normal safety precautions 
to avoid electrical shock.

NOTE:

 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 replace-
ment parts when servicing.

ELECTRICAL CONNECTION

This tool 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.

Summary of Contents for D551H

Page 1: ...operation and operator safety When 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 ma...

Page 2: ...Assembly 10 n Operation 10 14 n Maintenance 14 15 n Parts Ordering Service 16 TABLE OF CONTENTS INTRODUCTION This tool has many features for making its use more pleasant and enjoyable Safety performan...

Page 3: ...tool n Keep the tool and its handle dry clean and free from oil and grease Always use a clean cloth when clean ing Never use brake fluids gasoline petroleum based products or any strong solvents to cl...

Page 4: ...ed 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 a...

Page 5: ...njury user must read and understand operator s manual before using this product Eye Protection Always wear safety goggles or safety glasses with side shields or a full face shield when operating this...

Page 6: ...ially hazardous situation which if not avoided may result in minor or moderate injury CAUTION Without Safety Alert Symbol Indicates a situation that may result in property damage WARNING To avoid seri...

Page 7: ...ion cords before each use If damaged replace immediately Never use tool with a damaged cord since touching the damaged area could cause electrical shock resulting in serious injury DOUBLE INSULATION D...

Page 8: ...2 in 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 V 60 Hz AC only 5 5 Amps Net Weight 5 75 lbs Blows Per Minute AUXILIARY HANDLE ASSEMBLY D...

Page 9: ...perating in different positions and at different angles GRIPZONE OVERMOLD TECHNOLOGY The hammer drill features Gripzone overmold technology for improved comfort with a positive grip LOCK ON BUTTON The...

Page 10: ...ve care fully inspected and satisfactorily operated the tool n If any parts are damaged or missing please call 1 800 525 2579 for assistance PACKING LIST Hammer Drill Carrying Case Operator s Manual W...

Page 11: ...igure 3 This could cause the drill bit to be thrown from the drill resulting in possible serious injury or damage to the chuck n Insert the drill bit completely into the chuck n Tighten the chuck jaws...

Page 12: ...See Figure 7 CAUTION Never change gears while the tool is running Failure to obey this caution could result in serious damage to the drill The hammer drill has a two speed knob that provides a high s...

Page 13: ...mmer ing Failure to heed this caution may result in damage to the drill LOCKING ON See Figure 10 The lock on feature allows you to lock the drill on when you operate it continuously for extended perio...

Page 14: ...Plug the hammer drill into a power supply n Hold the drill firmly and place the bit at the point to be drilled n Depress the switch trigger to start the drill n Move the drill bit into the workpiece...

Page 15: ...he hex key sharply with a mallet in a clockwise direction n Open the chuck jaws and remove the hex key n Remove the chuck screw by turning it in a clockwise direction with a screwdriver NOTE The screw...

Page 16: ...l 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...

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